adding better error message

utils/generate_synthetic.py

@@ -308,7 +308,7 @@ def launch_main(img_in_real, img_in_synth, src, src_custom, dest, dest_custom, n
         return edit_pil[0]
 
     else:
-        raise ValueError(f"Invalid image type: {image_type}")
+        raise ValueError(f"Invalid image type found: {img_in_real} {img_in_synth}")