panic fix for 0 rows resolved (#1471)

* fix panic that occurs when a delete query against a conflict table affects 0 rows

* bats test for 0 conflict delete

* formatting

* fixes

go/libraries/doltcore/doltdb/table.go

@@ -42,6 +42,7 @@ const (
 
 var tableNameRegex, _ = regexp.Compile(TableNameRegexStr)
 
+var ErrNoConflictsResolved = errors.New("no conflicts resolved")
 var ErrNoAutoIncrementValue = fmt.Errorf("auto increment set for non-numeric column type")
 
 // IsValidTableName returns true if the name matches the regular expression TableNameRegexStr.
@@ -398,7 +399,7 @@ func (t *Table) ResolveConflicts(ctx context.Context, pkTuples []types.Value) (i
 	}
 
 	if removed == 0 {
-		return invalid, notFound, tbl, nil
+		return invalid, notFound, tbl, ErrNoConflictsResolved
 	}
 
 	conflicts, err := confEdit.Map(ctx)

go/libraries/doltcore/sqle/dtables/conflicts_tables.go

@@ -15,6 +15,8 @@ package dtables
 // limitations under the License.
 
 import (
+	"errors"
+
 	"github.com/dolthub/go-mysql-server/sql"
 
 	"github.com/dolthub/dolt/go/libraries/doltcore/doltdb"
@@ -159,6 +161,10 @@ func (cd *conflictDeleter) Close(ctx *sql.Context) error {
 	_, _, updatedTbl, err := cd.ct.tbl.ResolveConflicts(ctx, cd.pks)
 
 	if err != nil {
+		if errors.Is(err, doltdb.ErrNoConflictsResolved) {
+			return nil
+		}
+
 		return err
 	}
 

integration-tests/bats/conflict-detection.bats

@@ -926,7 +926,7 @@ SQL
     # Test resolve nonexistant key
     run dolt conflicts resolve foo 999
     [ "$status" -eq 1 ]
-    [[ "$output" =~ "not the primary key of a conflicting row" ]] || false
+    [[ "$output" =~ "no conflicts resolved" ]] || false
 
     dolt conflicts resolve --theirs foo
     run dolt sql -q 'select count(*) from foo'

integration-tests/bats/sql-conflicts.bats

@@ -78,6 +78,12 @@ teardown() {
   run dolt sql -r csv -q "SELECT * FROM dolt_conflicts"
   [ "$status" -eq 0 ]
   [[ "$output" =~ "$EXPECTED" ]] || false
+
+  # delete an already resolved conflict a 2nd time should not cause problems
+  run dolt sql -q "DELETE from dolt_conflicts_one_pk WHERE our_pk1 = 0"
+  [ "$status" -eq 0 ]
+  echo $output
+  [[ "$output" =~ "Query OK, 0 rows affected" ]] || false
 }