Address review comments

internal/internal_nexus_task_handler.go

@@ -233,8 +233,7 @@ func (h *nexusTaskHandler) handleStartOperation(
 				},
 			}, nil, nil
 		}
-		// Default to expose details for now. We may make this configurable eventually.
-		err = convertServiceError(convertApplicationError(err), true)
+		err = convertKnownErrors(err)
 		var handlerErr *nexus.HandlerError
 		if errors.As(err, &handlerErr) {
 			return nil, nexusHandlerErrorToProto(handlerErr), nil
@@ -306,8 +305,7 @@ func (h *nexusTaskHandler) handleCancelOperation(ctx context.Context, nctx *Nexu
 		return nil, nil, ctx.Err()
 	}
 	if err != nil {
-		// Default to expose details for now. We may make this configurable eventually.
-		err = convertServiceError(convertApplicationError(err), true)
+		err = convertKnownErrors(err)
 		var handlerErr *nexus.HandlerError
 		if errors.As(err, &handlerErr) {
 			return nil, nexusHandlerErrorToProto(handlerErr), nil
@@ -423,9 +421,17 @@ func (p *payloadSerializer) Serialize(v any) (*nexus.Content, error) {
 
 var emptyReaderNopCloser = io.NopCloser(bytes.NewReader([]byte{}))
 
-// statusGetter represents Temporal serviceerrors which have a Status() method.
-type statusGetter interface {
-	Status() *status.Status
+// convertKnownErrors converts a Temporal ApplicationError or a serviceerror to a Nexus HandlerError.
+func convertKnownErrors(err error) error {
+	// Not using errors.As to be consistent ApplicationError checking with the rest of the SDK.
+	if appErr, ok := err.(*ApplicationError); ok {
+		if appErr.NonRetryable() {
+			return nexus.HandlerErrorf(nexus.HandlerErrorTypeBadRequest, appErr.Error())
+		}
+		return nexus.HandlerErrorf(nexus.HandlerErrorTypeInternal, appErr.Error())
+	}
+	// Default to expose details for now. We will likely make this configurable eventually.
+	return convertServiceError(err, true)
 }
 
 // convertServiceError converts a serviceerror into a Nexus HandlerError if possible.
@@ -436,7 +442,11 @@ type statusGetter interface {
 // https://github.com/grpc-ecosystem/grpc-gateway/blob/a7cf811e6ffabeaddcfb4ff65602c12671ff326e/runtime/errors.go#L56.
 func convertServiceError(err error, exposeDetails bool) error {
 	var st *status.Status
-	var stGetter statusGetter
+
+	// Temporal serviceerrors have a Status() method.
+	var stGetter interface {
+		Status() *status.Status
+	}
 	if !errors.As(err, &stGetter) {
 		// Not a serviceerror, passthrough.
 		return err
@@ -499,16 +509,3 @@ func convertServiceError(err error, exposeDetails bool) error {
 	}
 	return err
 }
-
-// convertApplicationError converts a Temporal ApplicationError to a Nexus HandlerError, respecting the non_retryable
-// flag.
-func convertApplicationError(err error) error {
-	var appErr *ApplicationError
-	if errors.As(err, &appErr) {
-		if appErr.NonRetryable() {
-			return nexus.HandlerErrorf(nexus.HandlerErrorTypeBadRequest, appErr.Error())
-		}
-		return nexus.HandlerErrorf(nexus.HandlerErrorTypeInternal, appErr.Error())
-	}
-	return err
-}