fixed preprocessed result not shown and None return

app.py

@@ -86,8 +86,21 @@ def read_license_plate(license_plate_crop, ocr_engine='easyocr'):
     elif ocr_engine == 'paddleocr':
         result_raw = ocr_paddle.ocr(license_plate_crop)
         result_preprocessed = ocr_paddle.ocr(preprocessed_image)
-        detections_raw = [(None, result_raw[0][0][1][0], result_raw[0][0][1][1] if result_raw[0] else 0.0)]
-        detections_preprocessed = [(None, result_preprocessed[0][0][1][0], result_preprocessed[0][0][1][1] if result_preprocessed[0] else 0.0)]
+        
+        # no empty result
+        if result_raw and result_raw[0]:
+            detections_raw = [(None, result_raw[0][0][1][0], result_raw[0][0][1][1])]
+        else:
+            detections_raw = [(None, '', 0.0)]
+        
+        if result_preprocessed and result_preprocessed[0]:
+            detections_preprocessed = [(None, result_preprocessed[0][0][1][0], result_preprocessed[0][0][1][1])]
+        else:
+            detections_preprocessed = [(None, '', 0.0)]
+    else:
+        raise ValueError(f"OCR engine '{ocr_engine}' not supported.")
+    
+    return detections_raw, detections_preprocessed
     else:
         raise ValueError(f"OCR engine '{ocr_engine}' not supported.")