Customizing the error message for dolt init when a sql-server is already running from the directory

go/cmd/dolt/commands/init.go

@@ -104,6 +104,12 @@ func (cmd InitCmd) Exec(ctx context.Context, commandStr string, args []string, d
 		types.Format_Default = types.Format_DOLT
 	}
 
+	if dEnv.HasDoltSqlServerInfo() {
+		cli.PrintErrln(color.RedString("Detected that a Dolt sql-server is running from this directory. " +
+			"Stop the sql-server before initializing this directory as a Dolt database."))
+		return 1
+	}
+
 	name, _ := apr.GetValue(usernameParamName)
 	email, _ := apr.GetValue(emailParamName)
 	initBranch, _ := apr.GetValue(initBranchParamName)

go/libraries/doltcore/env/environment.go

@@ -303,6 +303,13 @@ func (dEnv *DoltEnv) HasDoltDataDir() bool {
 	return exists && isDir
 }
 
+// HasDoltSqlServerInfo returns true if this Dolt environment has a sql-server.info file, indicating
+// that a sql-server is running from this Dolt environment.
+func (dEnv *DoltEnv) HasDoltSqlServerInfo() bool {
+	exists, _ := dEnv.FS.Exists(filepath.Join(dbfactory.DoltDir, "sql-server.info"))
+	return exists
+}
+
 func (dEnv *DoltEnv) HasDoltTempTableDir() bool {
 	tmpDir, err := dEnv.TempTableFilesDir()
 	if err != nil {