Added alert message to Reset Layout if any of the panels from Query Tool failed to load. Fixes #5366

docs/en_US/release_notes_4_21.rst

@@ -50,6 +50,7 @@ Bug fixes
 | `Issue #5351 <https://redmine.postgresql.org/issues/5351>`_ -  Fixed compilation warnings while building pgAdmin.
 | `Issue #5361 <https://redmine.postgresql.org/issues/5361>`_ -  Fixes an issue where pgAdmin4 GUI does not display properly in IE 11.
 | `Issue #5362 <https://redmine.postgresql.org/issues/5362>`_ -  Fixed an issue where the identical packages and sequences visible as different in the schema diff tool.
+| `Issue #5366 <https://redmine.postgresql.org/issues/5366>`_ -  Added alert message to Reset Layout if any of the panels from Query Tool failed to load.
 | `Issue #5371 <https://redmine.postgresql.org/issues/5371>`_ -  Fixed tab key navigation for some dialogs.
 | `Issue #5383 <https://redmine.postgresql.org/issues/5383>`_ -  Fixed syntax error while refreshing the existing synonyms.
 | `Issue #5387 <https://redmine.postgresql.org/issues/5387>`_ -  Fixed an issue where the mode is not shown in the properties dialog of functions/procedures if all the arguments are "IN" arguments.

web/pgadmin/static/js/sqleditor/query_tool_notifications.js

@@ -104,7 +104,7 @@ let queryToolNotifications = {
     });
 
     // Render the grid
-    if (notifications_grid)
+    if (notifications_grid && notifications_panel)
       notifications_panel.$container.find('.sql-editor-notifications').append(notifications_grid.render().el);
   },
 

web/pgadmin/tools/sqleditor/static/js/sqleditor.js

@@ -330,6 +330,16 @@ define('tools.querytool', [
       self.messages_panel = self.docker.findPanels('messages')[0];
       self.notifications_panel = self.docker.findPanels('notifications')[0];
 
+      if (_.isUndefined(self.sql_panel_obj) || _.isUndefined(self.history_panel) ||
+       _.isUndefined(self.data_output_panel) || _.isUndefined(self.explain_panel) ||
+       _.isUndefined(self.messages_panel) || _.isUndefined(self.notifications_panel)) {
+        alertify.alert(
+          gettext('Panel Loading Error'),
+          gettext('Something went wrong while loading the panels.'
+          + ' Please make sure to reset the layout (File > Reset Layout) for the better user experience.')
+        );
+      }
+
       // Refresh Code mirror on SQL panel resize to
       // display its value properly
       self.sql_panel_obj.on(wcDocker.EVENT.RESIZE_ENDED, function() {