error generate in standalone mode

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

main.go

@@ -90,6 +90,9 @@ func (g *Generator) Generate(plugin *protogen.Plugin) error {
 			continue
 		case "micro":
 			err = g.microGenerate(component, plugin, genClient, genServer)
+			if err == nil {
+				err = g.writeErrors(plugin)
+			}
 		case "http":
 			err = g.httpGenerate(component, plugin, genClient, genServer)
 		case "grpc", "drpc", "rpc":
@@ -113,11 +116,6 @@ func (g *Generator) Generate(plugin *protogen.Plugin) error {
 
 	}
 
-	if err = g.writeErrors(plugin); err != nil {
-		plugin.Error(err)
-		return err
-	}
-
 	if err = g.astGenerate(plugin); err != nil {
 		plugin.Error(err)
 		return err

util.go

@@ -975,8 +975,10 @@ func (g *Generator) writeErrors(plugin *protogen.Plugin) error {
 	}
 
 	var gfile *protogen.GeneratedFile
+	var importPath protogen.GoImportPath
+
 	if len(errorsMap) > 0 {
-		gfile = plugin.NewGeneratedFile("micro_errors.pb.go", ".")
+
 		var packageName string
 
 		for _, file := range plugin.Files {
@@ -987,9 +989,16 @@ func (g *Generator) writeErrors(plugin *protogen.Plugin) error {
 				continue
 			}
 			packageName = string(file.GoPackageName)
+			importPath = file.GoImportPath
 			break
 		}
 
+		if g.standalone {
+			importPath = "."
+		}
+
+		gfile = plugin.NewGeneratedFile("micro_errors.pb.go", importPath)
+
 		gfile.P("// Code generated by protoc-gen-go-micro. DO NOT EDIT.")
 		gfile.P("// protoc-gen-go-micro version: " + versionComment)
 		gfile.P()
@@ -1009,6 +1018,11 @@ func (g *Generator) writeErrors(plugin *protogen.Plugin) error {
 			return err
 		}
 
+		for _, field := range msg.Fields {
+			if field.GoName == "Error" {
+				return fmt.Errorf("failed generate Error() string interface for %s message %s already have Error field", field.Location.SourceFile, msg.Desc.Name())
+			}
+		}
 		gfile.P(`func (m *`, msg.GoIdent.GoName, `) Error() string {`)
 		gfile.P(`buf, _ := marshaler.Marshal(m)`)
 		gfile.P("return string(buf)")