Fix delete mutations success message handling

Author: djhi

packages/ra-core/src/controller/button/useDeleteWithConfirmController.tsx

@@ -98,9 +98,11 @@ const useDeleteWithConfirmController = <
             onSuccess: () => {
                 setOpen(false);
                 notify(
-                    successMessage ?? isOffline
-                        ? `resources.${resource}.notifications.pending_delete`
-                        : `resources.${resource}.notifications.deleted`,
+                    successMessage != null
+                        ? successMessage
+                        : isOffline
+                          ? `resources.${resource}.notifications.pending_delete`
+                          : `resources.${resource}.notifications.deleted`,
                     {
                         type: 'info',
                         messageArgs: {

packages/ra-core/src/controller/button/useDeleteWithUndoController.tsx

@@ -71,9 +71,11 @@ const useDeleteWithUndoController = <
         {
             onSuccess: () => {
                 notify(
-                    successMessage ?? isOffline
-                        ? `resources.${resource}.notifications.pending_delete`
-                        : `resources.${resource}.notifications.deleted`,
+                    successMessage != null
+                        ? successMessage
+                        : isOffline
+                          ? `resources.${resource}.notifications.pending_delete`
+                          : `resources.${resource}.notifications.deleted`,
                     {
                         type: 'info',
                         messageArgs: {

packages/ra-ui-materialui/src/button/BulkDeleteWithConfirmButton.tsx

@@ -59,9 +59,11 @@ export const BulkDeleteWithConfirmButton = (
             onSuccess: () => {
                 refresh();
                 notify(
-                    successMessage ?? isOffline
-                        ? `resources.${resource}.notifications.pending_delete`
-                        : `resources.${resource}.notifications.deleted`,
+                    successMessage != null
+                        ? successMessage
+                        : isOffline
+                          ? `resources.${resource}.notifications.pending_delete`
+                          : `resources.${resource}.notifications.deleted`,
                     {
                         type: 'info',
                         messageArgs: {

packages/ra-ui-materialui/src/button/BulkDeleteWithUndoButton.tsx

@@ -52,9 +52,11 @@ export const BulkDeleteWithUndoButton = (
             {
                 onSuccess: () => {
                     notify(
-                        successMessage ?? isOffline
-                            ? `resources.${resource}.notifications.pending_delete`
-                            : `resources.${resource}.notifications.deleted`,
+                        successMessage != null
+                            ? successMessage
+                            : isOffline
+                              ? `resources.${resource}.notifications.pending_delete`
+                              : `resources.${resource}.notifications.deleted`,
                         {
                             type: 'info',
                             messageArgs: {