Add an `empty-answer' error type and remove images in this case.

annotating.py

@@ -270,7 +270,8 @@ def render_score_text(label, score, error, width_px, fontsize=18,
 def compose_label_image(base_img, label, result, hmin,
                         render_fn=render_latex_text,
                         draw_callback=None,
-                        with_error=True):
+                        with_error=True,
+                        with_empty=False):
     """
     Composes the final image with annotations.
 
@@ -287,6 +288,10 @@ def compose_label_image(base_img, label, result, hmin,
     error = result.get('error', "")
     feedbacks = result.get('feedback', [])
 
+    if error == "empty-answer" and not with_empty:
+        return None, 0
+
+
     # Filter deleted items (used by reading_annotations.py)
     feedbacks = [f for f in feedbacks if "to_delete" not in f]
 
@@ -436,12 +441,13 @@ def process_student(student_id, labels_data, root_dir, all_labels, overwrite):
         score = result.get('score', 0)
         d_notes[label] = str(score)
 
-        final_img, _ = compose_label_image(base_img, label, result, coordinates[0])
-
+        final_img, _ = compose_label_image(base_img, label, result, coordinates[0],
+                                           with_empty=True)
         # 7. Save Image
         save_path = os.path.join(output_dir, f"{label}.jpg")
         final_img.save(save_path)
-        label_images.append(final_img)
+        if result.get('error', "") != "empty-answer":
+            label_images.append(final_img)
 
     # Save scores
     with open(os.path.join(output_dir, "score.json"), "w") as f: