Don't schedule background post-startup activities if project has already been disposed (IDEA-CR-48118)

GitOrigin-RevId: fd382465106884b782965de73a99055386162c69

platform/platform-impl/src/com/intellij/openapi/project/impl/ProjectManagerImpl.java

@@ -429,7 +429,9 @@ public class ProjectManagerImpl extends ProjectManagerEx implements Disposable {
                                      ? LoadingPhase.PROJECT_OPENED
                                      : LoadingPhase.INDEXING_FINISHED);
 
-          startupManager.scheduleBackgroundPostStartupActivities();
+          if (!project.isDisposed()) {
+            startupManager.scheduleBackgroundPostStartupActivities();
+          }
         },
         ModalityState.NON_MODAL);
     }));