refactor pageDeletedHandler`s decision making.

packages/app/src/components/DescendantsPageList.tsx

@@ -62,12 +62,12 @@ export const DescendantsPageListSubstance = (props: SubstanceProps): JSX.Element
   }
 
   const pageDeletedHandler: OnDeletedFunction = useCallback((...args) => {
+    if (args[0] == null || args[2] == null) {
+      return;
+    }
     if (args[0] != null && args[2] != null) {
       toastSuccess(args[2] ? t('deleted_pages_completely', { path: args[0] }) : t('deleted_pages', { path: args[0] }));
     }
-    else {
-      return;
-    }
 
     advancePt();