handle list image upload with a single item

src/niceguiex/components/file_drop.py

@@ -174,7 +174,10 @@ class ImageDrop(FileDrop):
     def _handle_image_upload(self, data):
         """Convert file data to PIL Images before calling user callback"""
         if self._user_callback:
-            if isinstance(data, list):
+            if isinstance(data, list) and len(data) == 1:
+                img = Image.open(io.BytesIO(data[0]['content']))
+                self._user_callback(img)
+            elif isinstance(data, list):
                 # Multiple images - convert each to PIL Image
                 images = []
                 for file_data in data: