Fixed batch prediction

app.py

@@ -198,6 +198,8 @@ def prev_crop_preview() -> str:
     Preview for the current cropped image
     """
     global autocrop, current_image, temp_files
+    if current_image is None:
+        return None
     img = Image.open(current_image).convert("RGB")
     if autocrop:
         box = cropped_img(img)