fix: define image_file_buffer

app.py

@@ -80,11 +80,11 @@ with st.sidebar:
         # st.write(bytes_data)
 
     camera_click = st.button('Use my camera')
-
+    img_file_buffer = None
     if camera_click:
         img_file_buffer = st.camera_input("Take a picture of your receipt!")
     
-    if img_file_buffer is not None:
+    if img_file_buffer:
         # To read image file buffer as a PIL Image:
         photo = Image.open(img_file_buffer)