go: resolve various nilness issues

go/cmd/vtctldclient/command/vreplication/mount/mount.go

@@ -143,9 +143,7 @@ func commandList(cmd *cobra.Command, args []string) error {
 	if err != nil {
 		return err
 	}
-	if err != nil {
-		return err
-	}
+
 	data, err := json.Marshal(resp)
 	if err != nil {
 		return err

go/mysql/json/marshal.go

@@ -169,13 +169,12 @@ func MarshalSQLValue(buf []byte) (*sqltypes.Value, error) {
 	if len(buf) == 0 {
 		buf = sqltypes.NullBytes
 	}
+
 	jsonVal, err := parser.ParseBytes(buf)
 	if err != nil {
 		return nil, err
 	}
+
 	newVal := sqltypes.MakeTrusted(querypb.Type_JSON, jsonVal.MarshalSQLTo(nil))
-	if err != nil {
-		return nil, err
-	}
 	return &newVal, nil
 }

go/test/endtoend/cluster/cluster_process.go

@@ -765,19 +765,18 @@ func (cluster *LocalProcessCluster) populateVersionInfo() error {
 	return err
 }
 
+var versionRegex = regexp.MustCompile(`Version: ([0-9]+)\.([0-9]+)\.([0-9]+)`)
+
 func GetMajorVersion(binaryName string) (int, error) {
 	version, err := exec.Command(binaryName, "--version").Output()
 	if err != nil {
 		return 0, err
 	}
-	versionRegex := regexp.MustCompile(`Version: ([0-9]+)\.([0-9]+)\.([0-9]+)`)
 	v := versionRegex.FindStringSubmatch(string(version))
 	if len(v) != 4 {
 		return 0, fmt.Errorf("could not parse server version from: %s", version)
 	}
-	if err != nil {
-		return 0, fmt.Errorf("could not parse server version from: %s", version)
-	}
+
 	return strconv.Atoi(v[1])
 }
 

go/vt/binlog/binlogplayer/dbclient.go

@@ -183,8 +183,6 @@ func (dcr *dbClientImplWithSidecarDBReplacement) ExecuteFetchMulti(query string,
 		}
 		qps[i] = uq
 	}
-	if err != nil {
-		return nil, err
-	}
+
 	return dcr.dbClientImpl.ExecuteFetchMulti(strings.Join(qps, ";"), maxrows)
 }

go/vt/mysqlctl/mycnf.go

@@ -178,9 +178,7 @@ func ReadMycnf(mycnf *Mycnf, waitTime time.Duration) (*Mycnf, error) {
 	defer f.Close()
 
 	buf := bufio.NewReader(f)
-	if err != nil {
-		return nil, err
-	}
+
 	mycnf.mycnfMap = make(map[string]string)
 	var lval, rval string
 	var parts [][]byte

go/vt/mysqlctl/replication.go

@@ -237,7 +237,8 @@ func (mysqld *Mysqld) IsSuperReadOnly() (bool, error) {
 	if err != nil {
 		return false, err
 	}
-	if err == nil && len(qr.Rows) == 1 {
+
+	if len(qr.Rows) == 1 {
 		sro := qr.Rows[0][0].ToString()
 		if sro == "1" || sro == "ON" {
 			return true, nil

go/vt/schemadiff/schema.go

@@ -1041,10 +1041,8 @@ func (s *Schema) getTableColumnNames(t *CreateTableEntity) (columnNames []*sqlpa
 }
 
 // getViewColumnNames returns the names of aliased columns returned by a given view.
-func (s *Schema) getViewColumnNames(v *CreateViewEntity, schemaInformation *declarativeSchemaInformation) (
-	columnNames []*sqlparser.IdentifierCI,
-	err error,
-) {
+func (s *Schema) getViewColumnNames(v *CreateViewEntity, schemaInformation *declarativeSchemaInformation) ([]*sqlparser.IdentifierCI, error) {
+	var columnNames []*sqlparser.IdentifierCI
 	for _, node := range v.Select.GetColumns() {
 		switch node := node.(type) {
 		case *sqlparser.StarExpr:
@@ -1074,8 +1072,5 @@ func (s *Schema) getViewColumnNames(v *CreateViewEntity, schemaInformation *decl
 		}
 	}
 
-	if err != nil {
-		return nil, err
-	}
 	return columnNames, nil
 }

go/vt/sqlparser/parse_test.go

@@ -6346,7 +6346,7 @@ func parsePartial(r *bufio.Reader, readType []string, lineno int, fileName strin
 		if returnTypeNumber != -1 {
 			break
 		}
-		panic(fmt.Errorf("error reading file %s: line %d: %s - Expected keyword", fileName, lineno, err.Error()))
+		panic(fmt.Errorf("error reading file %s: line %d: Expected keyword", fileName, lineno))
 	}
 	input := ""
 	for {

go/vt/zkctl/zkconf.go

@@ -104,18 +104,16 @@ func MakeZooCfg(cnfFiles []string, cnf *ZkConfig, header string) (string, error)
 	for _, line := range strings.Split(header, "\n") {
 		fmt.Fprintf(&myTemplateSource, "## %v\n", strings.TrimSpace(line))
 	}
-	var dataErr error
+
 	for _, path := range cnfFiles {
-		data, dataErr := os.ReadFile(path)
-		if dataErr != nil {
+		data, err := os.ReadFile(path)
+		if err != nil {
 			continue
 		}
+
 		myTemplateSource.WriteString("## " + path + "\n")
 		myTemplateSource.Write(data)
 	}
-	if dataErr != nil {
-		return "", dataErr
-	}
 
 	myTemplateSource.WriteString("\n") // in case `data` did not end with a newline
 	for _, extra := range cnf.Extra {
@@ -126,9 +124,9 @@ func MakeZooCfg(cnfFiles []string, cnf *ZkConfig, header string) (string, error)
 	if err != nil {
 		return "", err
 	}
+
 	var cnfData strings.Builder
-	err = myTemplate.Execute(&cnfData, cnf)
-	if err != nil {
+	if err := myTemplate.Execute(&cnfData, cnf); err != nil {
 		return "", err
 	}
 	return cnfData.String(), nil