diff --git a/frontend/src/core/components/pageEditor/hooks/usePageDocument.ts b/frontend/src/core/components/pageEditor/hooks/usePageDocument.ts
index d2c04b53e..bd13fb0e1 100644
--- a/frontend/src/core/components/pageEditor/hooks/usePageDocument.ts
+++ b/frontend/src/core/components/pageEditor/hooks/usePageDocument.ts
@@ -206,7 +206,7 @@ export function usePageDocument(): PageDocumentHook {
     }));
 
     const currentPagesSet = currentPages ? new Set(currentPages.map(page => page.id)) : null;
-    if (currentPagesSet && currentPagesSet.size === pages.length) {
+    if (currentPagesSet && currentPages && currentPagesSet.size === pages.length) {
       const sameIds = pages.every(page => currentPagesSet.has(page.id));
       if (sameIds) {
         const mergedById = new Map(pages.map(page => [page.id, page]));
diff --git a/frontend/src/core/components/shared/pageEditor/useFileItemDragDrop.ts b/frontend/src/core/components/shared/pageEditor/useFileItemDragDrop.ts
index 6666340f1..2503957de 100644
--- a/frontend/src/core/components/shared/pageEditor/useFileItemDragDrop.ts
+++ b/frontend/src/core/components/shared/pageEditor/useFileItemDragDrop.ts
@@ -10,7 +10,7 @@ interface UseFileItemDragDropParams {
 }
 
 interface UseFileItemDragDropReturn {
-  itemRef: React.RefObject<HTMLDivElement>;
+  itemRef: React.RefObject<HTMLDivElement | null>;
   isDragging: boolean;
   isDragOver: boolean;
   dropPosition: 'above' | 'below';