Add runtime failure message for impossible situations

go/cmd/dolt/commands/diff.go

@@ -434,7 +434,7 @@ func (dArgs *diffArgs) applyDiffRoots(queryist cli.Queryist, sqlCtx *sql.Context
 	fromRef := args[0]
 	// treat the first arg as a ref spec
 	_, err := getTableNamesAtRef(queryist, sqlCtx, fromRef)
-	if errors.Is(err, doltdb.ErrUnexpectedGhostCommit) {
+	if errors.Is(err, doltdb.ErrGhostCommitEncountered) {
 		return nil, err
 	}
 	// if it doesn't resolve, treat it as a table name

go/cmd/dolt/commands/engine/sql_print.go

@@ -158,7 +158,7 @@ func writeResultSet(ctx *sql.Context, rowIter sql.RowIter, wr table.SqlRowWriter
 	i := 0
 	for {
 		r, err := rowIter.Next(ctx)
-		if err == io.EOF || err == doltdb.ErrUnexpectedGhostCommit {
+		if err == io.EOF || err == doltdb.ErrGhostCommitEncountered {
 			break
 		} else if err != nil {
 			return 0, err

go/cmd/dolt/commands/filter-branch.go

@@ -201,7 +201,7 @@ func getNerf(ctx context.Context, dEnv *env.DoltEnv, apr *argparser.ArgParseResu
 	}
 	cm, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, doltdb.ErrUnexpectedGhostCommit
+		return nil, doltdb.ErrGhostCommitEncountered
 	}
 
 	return rebase.StopAtCommit(cm), nil

go/cmd/dolt/commands/read_tables.go

@@ -223,7 +223,7 @@ func getRemoteDBAtCommit(ctx context.Context, remoteUrl string, remoteUrlParams
 	}
 	cm, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, nil, errhand.BuildDError(doltdb.ErrUnexpectedGhostCommit.Error()).Build()
+		return nil, nil, errhand.BuildDError(doltdb.ErrGhostCommitEncountered.Error()).Build()
 	}
 
 	srcRoot, err := cm.GetRootValue(ctx)

go/cmd/dolt/commands/show.go

@@ -284,7 +284,7 @@ func printObjects(ctx context.Context, dEnv *env.DoltEnv, opts *showOpts) error
 		}
 		commit, ok := optCmt.ToCommit()
 		if !ok {
-			return doltdb.ErrUnexpectedGhostCommit
+			return doltdb.ErrGhostCommitEncountered
 		}
 
 		value := commit.Value()

go/cmd/dolt/commands/stashcmds/pop.go

@@ -150,7 +150,7 @@ func applyStashAtIdx(ctx *sql.Context, dEnv *env.DoltEnv, curWorkingRoot *doltdb
 	if !ok {
 		// Should not be possible to get into this situation. The parent of the stashed commit
 		// Must have been present at the time it was created
-		return false, doltdb.ErrUnexpectedGhostCommit
+		return false, doltdb.ErrGhostCommitEncountered
 	}
 
 	parentRoot, err := parentCommit.GetRootValue(ctx)

go/cmd/dolt/commands/stashcmds/stash.go

@@ -233,7 +233,7 @@ func stashChanges(ctx context.Context, dEnv *env.DoltEnv, apr *argparser.ArgPars
 	}
 	commit, ok := optCmt.ToCommit()
 	if !ok {
-		return doltdb.ErrUnexpectedGhostCommit
+		return doltdb.ErrGhostCommitEncountered
 	}
 
 	commitMeta, err := commit.GetCommitMeta(ctx)

go/libraries/doltcore/cherry_pick/cherry_pick.go

@@ -210,7 +210,7 @@ func cherryPick(ctx *sql.Context, dSess *dsess.DoltSession, roots doltdb.Roots,
 	}
 	cherryCommit, ok := optCmt.ToCommit()
 	if err != nil {
-		return nil, "", doltdb.ErrUnexpectedGhostCommit
+		return nil, "", doltdb.ErrGhostCommitEncountered
 	}
 
 	if len(cherryCommit.DatasParents()) > 1 {
@@ -233,7 +233,7 @@ func cherryPick(ctx *sql.Context, dSess *dsess.DoltSession, roots doltdb.Roots,
 	}
 	parentCommit, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, "", doltdb.ErrUnexpectedGhostCommit
+		return nil, "", doltdb.ErrGhostCommitEncountered
 	}
 
 	parentRoot, err := parentCommit.GetRootValue(ctx)

go/libraries/doltcore/doltdb/commit.go

@@ -32,7 +32,8 @@ var errHasNoRootValue = errors.New("no root value")
 // TODO: Include the commit id in the error. Unfortunately, this message is passed through the SQL layer. The only way we currently
 // have on the client side to match an error is with string matching. We possibly need error codes as a prefix to the error message, but
 // currently there is not standard for doing this in Dolt.
-var ErrUnexpectedGhostCommit = errors.New("Commit not found. You are using a shallow clone which does not contain the requested commit. Please do a full clone.")
+var ErrGhostCommitEncountered = errors.New("Commit not found. You are using a shallow clone which does not contain the requested commit. Please do a full clone.")
+var ErrGhostCommitRuntimeFailure = errors.New("runtime failure: Ghost commit encountered unexpectedly. Please report bug to: https://github.com/dolthub/dolt/issues")
 
 // Rootish is an object resolvable to a RootValue.
 type Rootish interface {
@@ -237,7 +238,7 @@ func (c *Commit) CanFastReverseTo(ctx context.Context, new *Commit) (bool, error
 
 	ancestor, ok := optAnc.ToCommit()
 	if !ok {
-		return false, ErrUnexpectedGhostCommit
+		return false, ErrGhostCommitEncountered
 	}
 	if ancestor == nil {
 		return false, errors.New("cannot perform fast forward merge; commits have no common ancestor")
@@ -279,7 +280,7 @@ func (c *Commit) GetAncestor(ctx context.Context, as *AncestorSpec) (*OptionalCo
 		var ok bool
 		hardInst, ok = optInst.ToCommit()
 		if !ok {
-			return nil, ErrUnexpectedGhostCommit
+			return nil, ErrGhostCommitEncountered
 		}
 	}
 

go/libraries/doltcore/doltdb/commit_itr.go

@@ -151,7 +151,7 @@ func HashToCommit(ctx context.Context, vrw types.ValueReadWriter, ns tree.NodeSt
 	}
 
 	if dc.IsGhost() {
-		return nil, ErrUnexpectedGhostCommit
+		return nil, ErrGhostCommitEncountered
 	}
 
 	return NewCommit(ctx, vrw, ns, dc)

go/libraries/doltcore/doltdb/doltdb.go

@@ -436,7 +436,7 @@ func (ddb *DoltDB) BootstrapShallowResolve(ctx context.Context, cs *CommitSpec)
 	}
 
 	if commitValue.IsGhost() {
-		return prolly.CommitClosure{}, ErrUnexpectedGhostCommit
+		return prolly.CommitClosure{}, ErrGhostCommitEncountered
 	}
 
 	return getCommitClosure(ctx, commitValue, ddb.vrw, ddb.ns)
@@ -477,7 +477,7 @@ func (ddb *DoltDB) ResolveCommitRef(ctx context.Context, ref ref.DoltRef) (*Comm
 	}
 
 	if commitVal.IsGhost() {
-		return nil, ErrUnexpectedGhostCommit
+		return nil, ErrGhostCommitEncountered
 	}
 
 	return NewCommit(ctx, ddb.vrw, ddb.ns, commitVal)
@@ -501,7 +501,7 @@ func (ddb *DoltDB) ResolveCommitRefAtRoot(ctx context.Context, ref ref.DoltRef,
 	}
 
 	if commitVal.IsGhost() {
-		return nil, ErrUnexpectedGhostCommit
+		return nil, ErrGhostCommitEncountered
 	}
 
 	return NewCommit(ctx, ddb.vrw, ddb.ns, commitVal)
@@ -770,7 +770,7 @@ func (ddb *DoltDB) CommitWithParentSpecs(ctx context.Context, valHash hash.Hash,
 
 		hardCommit, ok := cm.ToCommit()
 		if !ok {
-			return nil, ErrUnexpectedGhostCommit
+			return nil, ErrGhostCommitEncountered
 		}
 
 		parentCommits = append(parentCommits, hardCommit)
@@ -843,7 +843,7 @@ func (ddb *DoltDB) CommitValue(ctx context.Context, dref ref.DoltRef, val types.
 	}
 
 	if dc.IsGhost() {
-		return nil, ErrUnexpectedGhostCommit
+		return nil, ErrGhostCommitEncountered
 	}
 
 	return NewCommit(ctx, ddb.vrw, ddb.ns, dc)
@@ -1456,7 +1456,7 @@ func (ddb *DoltDB) CommitWithWorkingSet(
 	}
 
 	if dc.IsGhost() {
-		return nil, ErrUnexpectedGhostCommit
+		return nil, ErrGhostCommitEncountered
 	}
 
 	return NewCommit(ctx, ddb.vrw, ddb.ns, dc)

go/libraries/doltcore/doltdb/stash.go

@@ -64,7 +64,7 @@ func getStashList(ctx context.Context, ds datas.Dataset, vrw types.ValueReadWrit
 		}
 
 		if hc.IsGhost() {
-			return nil, ErrUnexpectedGhostCommit
+			return nil, ErrGhostCommitEncountered
 		}
 
 		headCommit, err := NewCommit(ctx, vrw, ns, hc)
@@ -119,7 +119,7 @@ func getStashAtIdx(ctx context.Context, ds datas.Dataset, vrw types.ValueReadWri
 	}
 
 	if hc.IsGhost() {
-		return nil, nil, nil, ErrUnexpectedGhostCommit
+		return nil, nil, nil, ErrGhostCommitEncountered
 	}
 
 	headCommit, err := NewCommit(ctx, vrw, ns, hc)

go/libraries/doltcore/doltdb/tag.go

@@ -44,7 +44,7 @@ func NewTag(ctx context.Context, name string, ds datas.Dataset, vrw types.ValueR
 	}
 
 	if dc.IsGhost() {
-		return nil, ErrUnexpectedGhostCommit
+		return nil, ErrGhostCommitEncountered
 	}
 
 	commit, err := NewCommit(ctx, vrw, ns, dc)

go/libraries/doltcore/doltdb/workingset.go

@@ -407,7 +407,7 @@ func newWorkingSet(ctx context.Context, name string, vrw types.ValueReadWriter,
 		}
 
 		if fromDCommit.IsGhost() {
-			return nil, ErrUnexpectedGhostCommit
+			return nil, ErrGhostCommitEncountered
 		}
 
 		commit, err := NewCommit(ctx, vrw, ns, fromDCommit)
@@ -463,7 +463,7 @@ func newWorkingSet(ctx context.Context, name string, vrw types.ValueReadWriter,
 		}
 
 		if datasOntoCommit.IsGhost() {
-			return nil, ErrUnexpectedGhostCommit
+			return nil, ErrGhostCommitEncountered
 		}
 
 		ontoCommit, err := NewCommit(ctx, vrw, ns, datasOntoCommit)

go/libraries/doltcore/env/actions/branch.go

@@ -102,7 +102,7 @@ func CopyBranchOnDB(ctx context.Context, ddb *doltdb.DoltDB, oldBranch, newBranc
 
 	commit, ok := cm.ToCommit()
 	if !ok {
-		return doltdb.ErrUnexpectedGhostCommit
+		return doltdb.ErrGhostCommitEncountered
 	}
 	return ddb.NewBranchAtCommit(ctx, newRef, commit, rsc)
 }
@@ -194,7 +194,7 @@ func validateBranchMergedIntoCurrentWorkingBranch(ctx context.Context, dbdata en
 	}
 	branchHead, ok := optCmt.ToCommit()
 	if !ok {
-		return doltdb.ErrUnexpectedGhostCommit
+		return doltdb.ErrGhostCommitEncountered
 	}
 
 	cwbCs, err := doltdb.NewCommitSpec("HEAD")
@@ -212,7 +212,7 @@ func validateBranchMergedIntoCurrentWorkingBranch(ctx context.Context, dbdata en
 	}
 	cwbHead, ok := optCmt.ToCommit()
 	if !ok {
-		return doltdb.ErrUnexpectedGhostCommit
+		return doltdb.ErrGhostCommitEncountered
 	}
 
 	isMerged, err := branchHead.CanFastForwardTo(ctx, cwbHead)
@@ -262,7 +262,7 @@ func validateBranchMergedIntoUpstream(ctx context.Context, dbdata env.DbData, br
 	}
 	remoteBranchHead, ok := optCmt.ToCommit()
 	if !ok {
-		return doltdb.ErrUnexpectedGhostCommit
+		return doltdb.ErrGhostCommitEncountered
 	}
 
 	optCmt, err = dbdata.Ddb.Resolve(ctx, cs, nil)
@@ -271,7 +271,7 @@ func validateBranchMergedIntoUpstream(ctx context.Context, dbdata env.DbData, br
 	}
 	localBranchHead, ok := optCmt.ToCommit()
 	if !ok {
-		return doltdb.ErrUnexpectedGhostCommit
+		return doltdb.ErrGhostCommitEncountered
 	}
 
 	canFF, err := localBranchHead.CanFastForwardTo(ctx, remoteBranchHead)
@@ -341,7 +341,7 @@ func CreateBranchOnDB(ctx context.Context, ddb *doltdb.DoltDB, newBranch, starti
 
 	cm, ok := optCmt.ToCommit()
 	if !ok {
-		return doltdb.ErrUnexpectedGhostCommit
+		return doltdb.ErrGhostCommitEncountered
 	}
 
 	err = ddb.NewBranchAtCommit(ctx, branchRef, cm, rsc)

go/libraries/doltcore/env/actions/checkout.go

@@ -242,7 +242,7 @@ func BranchHeadRoot(ctx context.Context, db *doltdb.DoltDB, brName string) (*dol
 
 	cm, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, doltdb.ErrUnexpectedGhostCommit
+		return nil, doltdb.ErrGhostCommitEncountered
 	}
 
 	branchRoot, err := cm.GetRootValue(ctx)

go/libraries/doltcore/env/actions/clone.go

@@ -264,7 +264,7 @@ func fullClone(ctx context.Context, srcDB *doltdb.DoltDB, dEnv *env.DoltEnv, src
 	}
 	cm, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, doltdb.ErrUnexpectedGhostCommit
+		return nil, doltdb.ErrGhostCommitEncountered
 	}
 
 	err = dEnv.DoltDB.DeleteAllRefs(ctx)

go/libraries/doltcore/env/actions/commitwalk/commitwalk.go

@@ -325,7 +325,6 @@ func (i *dotDotCommiterator) Next(ctx context.Context) (hash.Hash, *doltdb.Optio
 
 		commit, ok := nextC.commit.ToCommit()
 		if !ok {
-			// Preserve the Ghost commit. NM4 - TEST THIS PATH.
 			return nextC.hash, nextC.commit, nil
 		}
 

go/libraries/doltcore/env/actions/remotes.go

@@ -230,7 +230,7 @@ func PushToRemoteBranch(ctx context.Context, rsr env.RepoStateReader, tempTableD
 	}
 	cm, ok := optCmt.ToCommit()
 	if !ok {
-		return doltdb.ErrUnexpectedGhostCommit
+		return doltdb.ErrGhostCommitEncountered
 	}
 
 	newCtx, cancelFunc := context.WithCancel(ctx)
@@ -416,7 +416,8 @@ func FetchRemoteBranch(
 	}
 	srcDBCommit, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, doltdb.ErrUnexpectedGhostCommit // NM4 This really should never happen. The source db is always expected to have everything.
+		// This really should never happen. The source db is always expected to have everything.
+		return nil, doltdb.ErrGhostCommitRuntimeFailure
 	}
 
 	// The code is structured this way (different paths for progress chan v. not) so that the linter can understand there
@@ -599,7 +600,7 @@ func fetchRefSpecsWithDepth(
 		}
 		commit, ok := optCmt.ToCommit()
 		if !ok {
-			return doltdb.ErrUnexpectedGhostCommit // NM4 - This definitely needs its own error message. TEST THIS PATH.
+			return doltdb.ErrGhostCommitEncountered // NM4 - This definitely needs its own error message. TEST THIS PATH.
 		}
 
 		remoteTrackRef := newHead.Ref
@@ -634,9 +635,6 @@ func fetchRefSpecsWithDepth(
 	}
 
 	if mode.Prune {
-		if remote == nil { // NM4 - I think this can be reverted. remote should never be nil.
-			return fmt.Errorf("Runtime error: remote is nil")
-		}
 		err = pruneBranches(ctx, dbData, *remote, newHeads)
 		if err != nil {
 			return err
@@ -700,7 +698,7 @@ func updateSkipList(ctx context.Context, srcDB *doltdb.DoltDB, toFetch []hash.Ha
 		// Must resolve because we just fetched it.
 		commit, ok := optCmt.ToCommit()
 		if !ok {
-			return nil, nil, doltdb.ErrUnexpectedGhostCommit
+			return nil, nil, doltdb.ErrGhostCommitEncountered
 		}
 
 		for i := 0; i < commit.NumParents(); i++ {

go/libraries/doltcore/env/actions/reset.go

@@ -53,7 +53,7 @@ func resetHardTables(ctx context.Context, dbData env.DbData, cSpecStr string, ro
 
 		var ok bool
 		if newHead, ok = optCmt.ToCommit(); !ok {
-			return nil, doltdb.Roots{}, doltdb.ErrUnexpectedGhostCommit
+			return nil, doltdb.Roots{}, doltdb.ErrGhostCommitEncountered
 		}
 
 		roots.Head, err = newHead.GetRootValue(ctx)
@@ -249,7 +249,7 @@ func ResetSoftToRef(ctx context.Context, dbData env.DbData, cSpecStr string) (do
 	}
 	newHead, ok := optCmt.ToCommit()
 	if !ok {
-		return doltdb.Roots{}, doltdb.ErrUnexpectedGhostCommit
+		return doltdb.Roots{}, doltdb.ErrGhostCommitEncountered
 	}
 
 	foundRoot, err := newHead.GetRootValue(ctx)

go/libraries/doltcore/env/actions/tag.go

@@ -67,7 +67,7 @@ func CreateTagOnDB(ctx context.Context, ddb *doltdb.DoltDB, tagName, startPoint
 	}
 	cm, ok := optCmt.ToCommit()
 	if !ok {
-		return doltdb.ErrUnexpectedGhostCommit // NM4 - This probably needs a different message. Need a test for this one.
+		return doltdb.ErrGhostCommitEncountered
 	}
 
 	meta := datas.NewTagMeta(props.TaggerName, props.TaggerEmail, props.Description)

go/libraries/doltcore/env/actions/workspace.go

@@ -69,7 +69,7 @@ func CreateWorkspaceOnDB(ctx context.Context, ddb *doltdb.DoltDB, name, startPoi
 	}
 	cm, ok := optCmt.ToCommit()
 	if !ok {
-		return doltdb.ErrUnexpectedGhostCommit // Should never happen?? better error anyway. NM4 - Test?
+		return doltdb.ErrGhostCommitEncountered
 	}
 
 	return ddb.NewWorkspaceAtCommit(ctx, workRef, cm)
@@ -80,14 +80,10 @@ func IsWorkspaceOnDB(ctx context.Context, ddb *doltdb.DoltDB, str string) (bool,
 	return ddb.HasRef(ctx, dref)
 }
 
-/*
 func IsWorkspace(ctx context.Context, dEnv *env.DoltEnv, str string) (bool, error) {
 	return IsWorkspaceOnDB(ctx, dEnv.DoltDB, str)
 }
 
-*/
-
-/*
 func DeleteWorkspace(ctx context.Context, dEnv *env.DoltEnv, workspaceName string, opts DeleteOptions) error {
 	var dref ref.DoltRef
 	if opts.Remote {
@@ -110,8 +106,6 @@ func DeleteWorkspace(ctx context.Context, dEnv *env.DoltEnv, workspaceName strin
 	return DeleteWorkspaceOnDB(ctx, dEnv, dref, opts)
 }
 
-
-
 func DeleteWorkspaceOnDB(ctx context.Context, dEnv *env.DoltEnv, dref ref.DoltRef, opts DeleteOptions) error {
 	ddb := dEnv.DoltDB
 	hasRef, err := ddb.HasRef(ctx, dref)
@@ -132,9 +126,9 @@ func DeleteWorkspaceOnDB(ctx context.Context, dEnv *env.DoltEnv, dref ref.DoltRe
 		if err != nil {
 			return err
 		}
-		m, err := optCmt.ToCommit()
-		if err != nil {
-			panic("NM4") // Should never happen?? better error anyway.
+		m, ok := optCmt.ToCommit()
+		if !ok {
+			return doltdb.ErrGhostCommitEncountered
 		}
 
 		cs, err := doltdb.NewCommitSpec(dref.String())
@@ -146,9 +140,9 @@ func DeleteWorkspaceOnDB(ctx context.Context, dEnv *env.DoltEnv, dref ref.DoltRe
 		if err != nil {
 			return err
 		}
-		cm, err := optCmt.ToCommit()
-		if err != nil {
-			panic("NM4") // Should never happen?? better error anyway.
+		cm, ok := optCmt.ToCommit()
+		if !ok {
+			return doltdb.ErrGhostCommitEncountered
 		}
 
 		isMerged, _ := m.CanFastReverseTo(ctx, cm)
@@ -162,4 +156,3 @@ func DeleteWorkspaceOnDB(ctx context.Context, dEnv *env.DoltEnv, dref ref.DoltRe
 
 	return ddb.DeleteWorkspace(ctx, dref)
 }
-*/

go/libraries/doltcore/env/environment.go

@@ -281,7 +281,7 @@ func mergeStateToMergeState(ctx context.Context, mergeState *mergeState, db *dol
 
 	commit, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, doltdb.ErrUnexpectedGhostCommit
+		return nil, doltdb.ErrGhostCommitEncountered
 	}
 
 	pmwh := hash.Parse(mergeState.PreMergeWorking)

go/libraries/doltcore/merge/action.go

@@ -106,7 +106,7 @@ func NewMergeSpec(
 	}
 	headCM, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - need better message. TEST THIS PATH.
+		return nil, doltdb.ErrGhostCommitEncountered // NM4 - need better message. TEST THIS PATH.
 	}
 
 	mergeCS, err := doltdb.NewCommitSpec(commitSpecStr)
@@ -120,7 +120,7 @@ func NewMergeSpec(
 	}
 	mergeCM, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - need better message. TEST THIS PATH
+		return nil, doltdb.ErrGhostCommitEncountered // NM4 - need better message. TEST THIS PATH
 	}
 
 	headH, err := headCM.HashOf()

go/libraries/doltcore/merge/merge.go

@@ -54,7 +54,7 @@ func MergeCommits(ctx *sql.Context, commit, mergeCommit *doltdb.Commit, opts edi
 	}
 	ancCommit, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - not sure if we can get to this point. TEST THIS PATH.
+		return nil, doltdb.ErrGhostCommitEncountered // NM4 - not sure if we can get to this point. TEST THIS PATH.
 	}
 
 	ourRoot, err := commit.GetRootValue(ctx)

go/libraries/doltcore/merge/merge_base.go

@@ -29,7 +29,7 @@ func MergeBase(ctx context.Context, left, right *doltdb.Commit) (base hash.Hash,
 	}
 	ancestor, ok := optCmt.ToCommit()
 	if !ok {
-		return base, doltdb.ErrUnexpectedGhostCommit // NM4 - TEST.  I think getCommitAncestor is going to be an awk one.
+		return base, doltdb.ErrGhostCommitEncountered // NM4 - TEST.  I think getCommitAncestor is going to be an awk one.
 	}
 
 	return ancestor.HashOf()

go/libraries/doltcore/merge/revert.go

@@ -66,7 +66,7 @@ func Revert(ctx *sql.Context, ddb *doltdb.DoltDB, root *doltdb.RootValue, commit
 		}
 		parentCM, ok := optCmt.ToCommit()
 		if !ok {
-			return nil, "", doltdb.ErrUnexpectedGhostCommit // NM4 - TEST THIS PATH.
+			return nil, "", doltdb.ErrGhostCommitEncountered // NM4 - TEST THIS PATH.
 		}
 
 		theirRoot, err := parentCM.GetRootValue(ctx)

go/libraries/doltcore/migrate/transform.go

@@ -127,7 +127,7 @@ func migrateCommit(ctx context.Context, menv Environment, oldCm *doltdb.Commit,
 	}
 	oldParentCm, ok := optCmt.ToCommit()
 	if !ok {
-		return doltdb.ErrUnexpectedGhostCommit
+		return doltdb.ErrGhostCommitEncountered
 	}
 
 	oldParentRoot, err := oldParentCm.GetRootValue(ctx)
@@ -156,7 +156,7 @@ func migrateCommit(ctx context.Context, menv Environment, oldCm *doltdb.Commit,
 	}
 	newParentCm, ok := optCmt.ToCommit()
 	if !ok {
-		return doltdb.ErrUnexpectedGhostCommit
+		return doltdb.ErrGhostCommitEncountered
 	}
 
 	newParentRoot, err := newParentCm.GetRootValue(ctx)

go/libraries/doltcore/migrate/traverse.go

@@ -142,7 +142,7 @@ func traverseTagHistory(ctx context.Context, menv Environment, r ref.TagRef, old
 	}
 	cm, ok := optCmt.ToCommit()
 	if !ok {
-		return doltdb.ErrUnexpectedGhostCommit
+		return doltdb.ErrGhostCommitEncountered
 	}
 
 	return new.NewTagAtCommit(ctx, r, cm, t.Meta)
@@ -194,7 +194,7 @@ func traverseCommitHistory(ctx context.Context, menv Environment, cm *doltdb.Com
 		}
 		cm, ok = optCmt.ToCommit()
 		if !ok {
-			return doltdb.ErrUnexpectedGhostCommit
+			return doltdb.ErrGhostCommitEncountered
 		}
 	}
 }

go/libraries/doltcore/rebase/filter_branch.go

@@ -190,7 +190,7 @@ func rebaseRecursive(ctx context.Context, ddb *doltdb.DoltDB, replay ReplayCommi
 	for _, optParent := range allOptParents {
 		parent, ok := optParent.ToCommit()
 		if !ok {
-			return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - TEST, surely needs a better error.
+			return nil, doltdb.ErrGhostCommitEncountered // NM4 - TEST, surely needs a better error.
 		}
 		allParents = append(allParents, parent)
 	}

go/libraries/doltcore/rebase/rebase.go

@@ -202,7 +202,7 @@ func findRebaseCommits(ctx *sql.Context, currentBranchCommit, upstreamBranchComm
 
 		commit, ok := optCmt.ToCommit()
 		if !ok {
-			return nil, doltdb.ErrUnexpectedGhostCommit // Not sure if we can get this far. commit walk is going to be a bear.
+			return nil, doltdb.ErrGhostCommitEncountered // Not sure if we can get this far. commit walk is going to be a bear.
 		}
 
 		// Don't include merge commits in the rebase plan

go/libraries/doltcore/sqle/database.go

@@ -511,7 +511,7 @@ func resolveAsOfTime(ctx *sql.Context, ddb *doltdb.DoltDB, head ref.DoltRef, asO
 	}
 	cm, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, nil, doltdb.ErrUnexpectedGhostCommit // NM4 - NEED TEST.
+		return nil, nil, doltdb.ErrGhostCommitEncountered // NM4 - NEED TEST.
 	}
 
 	h, err := cm.HashOf()
@@ -533,7 +533,7 @@ func resolveAsOfTime(ctx *sql.Context, ddb *doltdb.DoltDB, head ref.DoltRef, asO
 		}
 		curr, ok := optCmt.ToCommit()
 		if !ok {
-			return nil, nil, doltdb.ErrUnexpectedGhostCommit // NM4 - NEED TEST.
+			return nil, nil, doltdb.ErrGhostCommitEncountered // NM4 - NEED TEST.
 		}
 
 		meta, err := curr.GetCommitMeta(ctx)
@@ -586,7 +586,7 @@ func resolveAsOfCommitRef(ctx *sql.Context, db Database, head ref.DoltRef, commi
 	}
 	cm, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, nil, doltdb.ErrUnexpectedGhostCommit // NM4 - NEED TEST.
+		return nil, nil, doltdb.ErrGhostCommitEncountered // NM4 - NEED TEST.
 	}
 
 	root, err := cm.GetRootValue(ctx)

go/libraries/doltcore/sqle/database_provider.go

@@ -1087,7 +1087,7 @@ func resolveAncestorSpec(ctx *sql.Context, revSpec string, ddb *doltdb.DoltDB) (
 	ok := false
 	cm, ok = optCmt.ToCommit()
 	if !ok {
-		return "", doltdb.ErrUnexpectedGhostCommit // NM4 - NEED TEST.
+		return "", doltdb.ErrGhostCommitEncountered // NM4 - NEED TEST.
 	}
 
 	hash, err := cm.HashOf()
@@ -1482,7 +1482,7 @@ func initialStateForCommit(ctx context.Context, srcDb ReadOnlyDatabase) (dsess.I
 	}
 	cm, ok := optCmt.ToCommit()
 	if !ok {
-		return dsess.InitialDbState{}, doltdb.ErrUnexpectedGhostCommit // NM4 - NEED TEST???
+		return dsess.InitialDbState{}, doltdb.ErrGhostCommitEncountered // NM4 - NEED TEST???
 	}
 
 	init := dsess.InitialDbState{

go/libraries/doltcore/sqle/dfunctions/dolt_merge_base.go

@@ -105,7 +105,7 @@ func resolveRefSpecs(ctx *sql.Context, leftSpec, rightSpec string) (left, right
 	}
 	left, ok = optCmt.ToCommit()
 	if !ok {
-		return nil, nil, doltdb.ErrUnexpectedGhostCommit // NM4 - TEST, surely needs a better error.
+		return nil, nil, doltdb.ErrGhostCommitEncountered // NM4 - TEST, surely needs a better error.
 	}
 
 	optCmt, err = doltDB.Resolve(ctx, rcs, headRef)
@@ -114,7 +114,7 @@ func resolveRefSpecs(ctx *sql.Context, leftSpec, rightSpec string) (left, right
 	}
 	right, ok = optCmt.ToCommit()
 	if !ok {
-		return nil, nil, doltdb.ErrUnexpectedGhostCommit // NM4 - TEST, surely needs a better error.
+		return nil, nil, doltdb.ErrGhostCommitEncountered // NM4 - TEST, surely needs a better error.
 	}
 
 	return

go/libraries/doltcore/sqle/dfunctions/has_ancestor.go

@@ -80,7 +80,7 @@ func (a *HasAncestor) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
 		}
 		headCommit, ok = optCmt.ToCommit()
 		if !ok {
-			return nil, doltdb.ErrUnexpectedGhostCommit
+			return nil, doltdb.ErrGhostCommitEncountered
 		}
 	}
 
@@ -104,7 +104,7 @@ func (a *HasAncestor) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
 		}
 		ancCommit, ok = optCmt.ToCommit()
 		if !ok {
-			return nil, doltdb.ErrUnexpectedGhostCommit
+			return nil, doltdb.ErrGhostCommitEncountered
 		}
 
 	}

go/libraries/doltcore/sqle/dfunctions/hashof.go

@@ -91,7 +91,7 @@ func (t *HashOf) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
 				}
 				cm, ok = optCmt.ToCommit()
 				if !ok {
-					return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - TEST this.
+					return nil, doltdb.ErrGhostCommitEncountered // NM4 - TEST this.
 				}
 			} else {
 				return nil, err
@@ -110,7 +110,7 @@ func (t *HashOf) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
 	}
 	cm, ok = optCmt.ToCommit()
 	if !ok {
-		return nil, doltdb.ErrUnexpectedGhostCommit
+		return nil, doltdb.ErrGhostCommitEncountered
 	}
 
 	h, err := cm.HashOf()

go/libraries/doltcore/sqle/dolt_diff_table_function.go

@@ -337,7 +337,7 @@ func resolveCommit(ctx *sql.Context, ddb *doltdb.DoltDB, headRef ref.DoltRef, cS
 	}
 	cm, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - NEED TEST.
+		return nil, doltdb.ErrGhostCommitEncountered // NM4 - NEED TEST.
 	}
 
 	return cm, nil

go/libraries/doltcore/sqle/dolt_log_table_function.go

@@ -443,7 +443,7 @@ func (ltf *LogTableFunction) RowIter(ctx *sql.Context, row sql.Row) (sql.RowIter
 		}
 		commit, ok = optCmt.ToCommit()
 		if err != nil {
-			return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - TEST.
+			return nil, doltdb.ErrGhostCommitEncountered // NM4 - TEST.
 		}
 
 		commits = append(commits, commit)
@@ -462,7 +462,7 @@ func (ltf *LogTableFunction) RowIter(ctx *sql.Context, row sql.Row) (sql.RowIter
 		}
 		notCommit, ok := optCmt.ToCommit()
 		if !ok {
-			return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - TEST.
+			return nil, doltdb.ErrGhostCommitEncountered // NM4 - TEST.
 		}
 
 		notCommits = append(notCommits, notCommit)
@@ -486,7 +486,7 @@ func (ltf *LogTableFunction) RowIter(ctx *sql.Context, row sql.Row) (sql.RowIter
 		}
 		mergeCommit, ok := optCmt.ToCommit()
 		if !ok {
-			return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - TEST.
+			return nil, doltdb.ErrGhostCommitEncountered // NM4 - TEST.
 		}
 
 		notCommits = append(notCommits, mergeCommit)
@@ -678,7 +678,7 @@ func (itr *logTableFunctionRowIter) Next(ctx *sql.Context) (sql.Row, error) {
 		ok := false
 		commit, ok = optCmt.ToCommit()
 		if !ok {
-			return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - TEST.
+			return nil, doltdb.ErrGhostCommitEncountered // NM4 - TEST.
 		}
 
 		if itr.tableNames != nil {
@@ -693,7 +693,7 @@ func (itr *logTableFunctionRowIter) Next(ctx *sql.Context) (sql.Row, error) {
 			}
 			parent0Cm, ok := optCmt.ToCommit()
 			if !ok {
-				return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - TEST.
+				return nil, doltdb.ErrGhostCommitEncountered // NM4 - TEST.
 			}
 
 			var parent1Cm *doltdb.Commit
@@ -704,7 +704,7 @@ func (itr *logTableFunctionRowIter) Next(ctx *sql.Context) (sql.Row, error) {
 				}
 				parent1Cm, ok = optCmt.ToCommit()
 				if !ok {
-					return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - TEST.
+					return nil, doltdb.ErrGhostCommitEncountered // NM4 - TEST.
 				}
 			}
 

go/libraries/doltcore/sqle/dprocedures/dolt_count_commits.go

@@ -82,7 +82,7 @@ func countCommits(ctx *sql.Context, args ...string) (ahead uint64, behind uint64
 	}
 	fromCommit, ok := optCmt.ToCommit()
 	if !ok {
-		return 0, 0, doltdb.ErrUnexpectedGhostCommit // NM4 - Have no idea what this is
+		return 0, 0, doltdb.ErrGhostCommitEncountered // NM4 - Have no idea what this is
 	}
 
 	fromHash, err := fromCommit.HashOf()
@@ -100,7 +100,7 @@ func countCommits(ctx *sql.Context, args ...string) (ahead uint64, behind uint64
 	}
 	toCommit, ok := optCmt.ToCommit()
 	if !ok {
-		return 0, 0, doltdb.ErrUnexpectedGhostCommit // NM4 - Have no idea what this is
+		return 0, 0, doltdb.ErrGhostCommitEncountered // NM4 - Have no idea what this is
 	}
 
 	toHash, err := toCommit.HashOf()
@@ -114,7 +114,7 @@ func countCommits(ctx *sql.Context, args ...string) (ahead uint64, behind uint64
 	}
 	ancestor, ok := optCmt.ToCommit()
 	if !ok {
-		return 0, 0, doltdb.ErrUnexpectedGhostCommit // NM4 - Have no idea what this is
+		return 0, 0, doltdb.ErrGhostCommitEncountered // NM4 - Have no idea what this is
 	}
 
 	ancestorHash, err := ancestor.HashOf()

go/libraries/doltcore/sqle/dprocedures/dolt_rebase.go

@@ -199,7 +199,7 @@ func startRebase(ctx *sql.Context, upstreamPoint string) error {
 	}
 	upstreamCommit, ok := optCmt.ToCommit()
 	if !ok {
-		return doltdb.ErrUnexpectedGhostCommit // NM4 - prob user input. TEST. message.
+		return doltdb.ErrGhostCommitEncountered // NM4 - prob user input. TEST. message.
 	}
 
 	// rebaseWorkingBranch is the name of the temporary branch used when performing a rebase. In Git, a rebase
@@ -565,7 +565,7 @@ func squashCommitMessage(ctx *sql.Context, nextCommitHash string) (string, error
 	}
 	nextCommit, ok := optCmt.ToCommit()
 	if !ok {
-		return "", doltdb.ErrUnexpectedGhostCommit // NM4 - TEST.
+		return "", doltdb.ErrGhostCommitEncountered // NM4 - TEST.
 	}
 
 	nextCommitMeta, err := nextCommit.GetCommitMeta(ctx)

go/libraries/doltcore/sqle/dprocedures/dolt_revert.go

@@ -104,7 +104,7 @@ func doDoltRevert(ctx *sql.Context, args []string) (int, error) {
 		}
 		commit, ok := optCmt.ToCommit()
 		if !ok {
-			return 1, doltdb.ErrUnexpectedGhostCommit // NM4 TEST - I think should never happen.
+			return 1, doltdb.ErrGhostCommitEncountered // NM4 TEST - I think should never happen.
 		}
 
 		commits[i] = commit

go/libraries/doltcore/sqle/dsess/session.go

@@ -415,7 +415,7 @@ func (d *DoltSession) newWorkingSetForHead(ctx *sql.Context, wsRef ref.WorkingSe
 	}
 	headCommit, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, doltdb.ErrUnexpectedGhostCommit
+		return nil, doltdb.ErrGhostCommitEncountered
 	}
 
 	headRoot, err := headCommit.GetRootValue(ctx)
@@ -697,7 +697,7 @@ func (d *DoltSession) newPendingCommit(ctx *sql.Context, branchState *branchStat
 			}
 			parentCommit, ok := optCmt.ToCommit()
 			if !ok {
-				return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - TEST THIS PATH.
+				return nil, doltdb.ErrGhostCommitEncountered // NM4 - TEST THIS PATH.
 			}
 
 			mergeParentCommits = append(mergeParentCommits, parentCommit)
@@ -897,7 +897,7 @@ func (d *DoltSession) ResolveRootForRef(ctx *sql.Context, dbName, refStr string)
 	}
 	cm, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, nil, "", doltdb.ErrUnexpectedGhostCommit
+		return nil, nil, "", doltdb.ErrGhostCommitEncountered
 	}
 
 	root, err = cm.GetRootValue(ctx)

go/libraries/doltcore/sqle/dsess/transactions.go

@@ -208,7 +208,7 @@ func doltCommit(ctx *sql.Context,
 	}
 	curHead, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, nil, doltdb.ErrUnexpectedGhostCommit // NM4 - def runtime error.
+		return nil, nil, doltdb.ErrGhostCommitEncountered // NM4 - def runtime error.
 	}
 
 	// We already got a new staged root via merge or ff via the doCommit method, so now apply it to the STAGED value

go/libraries/doltcore/sqle/dtables/column_diff_table.go

@@ -342,7 +342,7 @@ func (itr *doltColDiffCommitHistoryRowItr) Next(ctx *sql.Context) (sql.Row, erro
 			}
 			commit, ok := optCmt.ToCommit()
 			if !ok {
-				return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - TEST, message.
+				return nil, doltdb.ErrGhostCommitEncountered // NM4 - TEST, message.
 			}
 
 			err = itr.loadTableChanges(ctx, commit)
@@ -420,7 +420,7 @@ func (itr *doltColDiffCommitHistoryRowItr) calculateTableChanges(ctx context.Con
 	}
 	parent, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - TEST, message.
+		return nil, doltdb.ErrGhostCommitEncountered // NM4 - TEST, message.
 	}
 
 	fromRootValue, err := parent.GetRootValue(ctx)

go/libraries/doltcore/sqle/dtables/commit_ancestors_table.go

@@ -166,7 +166,7 @@ func (itr *CommitAncestorsRowItr) Next(ctx *sql.Context) (sql.Row, error) {
 
 		cm, ok := optCmt.ToCommit()
 		if !ok {
-			return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - I think this will happen plenty. TEST.
+			return nil, doltdb.ErrGhostCommitEncountered // NM4 - I think this will happen plenty. TEST.
 		}
 
 		parents, err := itr.ddb.ResolveAllParents(ctx, cm)
@@ -183,7 +183,7 @@ func (itr *CommitAncestorsRowItr) Next(ctx *sql.Context) (sql.Row, error) {
 		for i, optParent := range parents {
 			p, ok := optParent.ToCommit()
 			if !ok {
-				return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - TEST.
+				return nil, doltdb.ErrGhostCommitEncountered // NM4 - TEST.
 			}
 
 			ph, err := p.HashOf()

go/libraries/doltcore/sqle/dtables/commit_diff_table.go

@@ -271,7 +271,7 @@ func (dt *CommitDiffTable) rootValForHash(ctx *sql.Context, hashStr string) (*do
 		}
 		cm, ok := optCmt.ToCommit()
 		if !ok {
-			return nil, "", nil, doltdb.ErrUnexpectedGhostCommit
+			return nil, "", nil, doltdb.ErrGhostCommitEncountered
 		}
 
 		root, err = cm.GetRootValue(ctx)

go/libraries/doltcore/sqle/dtables/commits_table.go

@@ -156,7 +156,7 @@ func (itr CommitsRowItr) Next(ctx *sql.Context) (sql.Row, error) {
 	}
 	cm, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - NEED TEST.
+		return nil, doltdb.ErrGhostCommitEncountered // NM4 - NEED TEST.
 	}
 
 	meta, err := cm.GetCommitMeta(ctx)

go/libraries/doltcore/sqle/dtables/diff_table.go

@@ -406,7 +406,7 @@ func (dt *DiffTable) reverseIterForChild(ctx *sql.Context, parent hash.Hash) (*d
 
 		childCm, ok := optCmt.ToCommit()
 		if !ok {
-			return nil, hash.Hash{}, doltdb.ErrUnexpectedGhostCommit
+			return nil, hash.Hash{}, doltdb.ErrGhostCommitEncountered
 		}
 
 		phs, err := childCm.ParentHashes(ctx)
@@ -518,7 +518,7 @@ func (dt *DiffTable) toCommitLookupPartitions(ctx *sql.Context, hashes []hash.Ha
 			}
 			pc, ok := optCmt.ToCommit()
 			if !ok {
-				return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - NEED TEST.
+				return nil, doltdb.ErrGhostCommitEncountered // NM4 - NEED TEST.
 			}
 
 			cmHashToTblInfo[pj] = toCmInfo
@@ -803,7 +803,7 @@ func (dps *DiffPartitions) Next(ctx *sql.Context) (sql.Partition, error) {
 		}
 		cm, ok := optCmt.ToCommit()
 		if !ok {
-			return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - NEED TEST.
+			return nil, doltdb.ErrGhostCommitEncountered // NM4 - NEED TEST.
 		}
 
 		root, err := cm.GetRootValue(ctx)

go/libraries/doltcore/sqle/dtables/log_table.go

@@ -238,7 +238,7 @@ func (itr *LogItr) Next(ctx *sql.Context) (sql.Row, error) {
 
 	cm, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - NEED TEST.
+		return nil, doltdb.ErrGhostCommitEncountered // NM4 - NEED TEST.
 	}
 
 	meta, err := cm.GetCommitMeta(ctx)

go/libraries/doltcore/sqle/dtables/schema_conflicts_table.go

@@ -109,7 +109,7 @@ func (dt *SchemaConflictsTable) PartitionRows(ctx *sql.Context, part sql.Partiti
 	}
 	base, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - NEED TEST.
+		return nil, doltdb.ErrGhostCommitEncountered // NM4 - NEED TEST.
 	}
 
 	baseRoot, err := base.GetRootValue(ctx)

go/libraries/doltcore/sqle/dtables/unscoped_diff_table.go

@@ -337,7 +337,7 @@ func (itr *doltDiffCommitHistoryRowItr) Next(ctx *sql.Context) (sql.Row, error)
 			}
 			commit, ok := optCmt.ToCommit()
 			if !ok {
-				return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - TEST.
+				return nil, doltdb.ErrGhostCommitEncountered // NM4 - TEST.
 			}
 
 			err = itr.loadTableChanges(ctx, commit)
@@ -412,7 +412,7 @@ func (itr *doltDiffCommitHistoryRowItr) calculateTableChanges(ctx context.Contex
 	}
 	parent, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, doltdb.ErrUnexpectedGhostCommit // NM4 - TEST.
+		return nil, doltdb.ErrGhostCommitEncountered // NM4 - TEST.
 	}
 
 	fromRootValue, err := parent.GetRootValue(ctx)

go/libraries/doltcore/sqle/history_table.go

@@ -458,7 +458,7 @@ func (cp commitPartitioner) Next(ctx *sql.Context) (sql.Partition, error) {
 	}
 	cm, ok := optCmt.ToCommit()
 	if !ok {
-		return nil, doltdb.ErrUnexpectedGhostCommit // NM4 TEST.
+		return nil, doltdb.ErrGhostCommitEncountered // NM4 TEST.
 	}
 
 	return &commitPartition{h, cm}, nil

go/libraries/doltcore/sqle/read_replica_database.go

@@ -412,7 +412,7 @@ func (rrd ReadReplicaDatabase) createNewBranchFromRemote(ctx *sql.Context, remot
 	}
 	cm, ok := optCmt.ToCommit()
 	if !ok {
-		return doltdb.ErrUnexpectedGhostCommit // NM4 - TEST.
+		return doltdb.ErrGhostCommitEncountered // NM4 - TEST.
 	}
 
 	err = rrd.ddb.NewBranchAtCommit(ctx, remoteRef.Ref, cm, nil)