From de017e07519eacd3ddda3f3ec66e404cda540d39 Mon Sep 17 00:00:00 2001
From: Reece <reece@stirlingpdf.com>
Date: Sat, 31 Jan 2026 14:34:26 +0000
Subject: [PATCH] validate cache

---
 frontend/src/core/hooks/useThumbnailGeneration.ts | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/frontend/src/core/hooks/useThumbnailGeneration.ts b/frontend/src/core/hooks/useThumbnailGeneration.ts
index a2b251786f..ecf8b4ef6e 100644
--- a/frontend/src/core/hooks/useThumbnailGeneration.ts
+++ b/frontend/src/core/hooks/useThumbnailGeneration.ts
@@ -76,6 +76,16 @@ async function processRequestQueue() {
           let arrayBuffer = fileArrayBufferCache.get(file);
           if (!arrayBuffer) {
             arrayBuffer = await file.arrayBuffer();
+
+            // Validate ArrayBuffer is not empty before caching
+            if (!arrayBuffer || arrayBuffer.byteLength === 0) {
+              console.warn(`Skipping thumbnail generation for ${file.name}: file is empty or not loaded yet`);
+              // Don't cache empty buffers - allow retry later when file is loaded
+              // Resolve all requests with null (no thumbnail)
+              requests.forEach(request => request.resolve(null));
+              continue;
+            }
+
             fileArrayBufferCache.set(file, arrayBuffer);
           }