diff --git a/assets/js/page_image_detail.js b/assets/js/page_image_detail.js
index 2ab2a686a60a9a497582a2b67cc1eaa614ff14bd..220e6b6cca89ff5f9ddf2a0b2d8c3a9de046450b 100644
--- a/assets/js/page_image_detail.js
+++ b/assets/js/page_image_detail.js
@@ -30,8 +30,10 @@ const currentState = () => {
 
 const formDataToJson = (data) => {
     const result = {};
-    for (let key of data.keys()) {
-        result[key] = data.getAll(key);
+    if (data != null) {
+        for (let key of data.keys()) {
+            result[key] = data.getAll(key);
+        }
     }
     return result;
 };