Fix empty_contours_guard patch: use gray_image (correct param name) not alpha

app.py

@@ -214,16 +214,17 @@ def load_triposg():
         # Patch find_bounding_box: guard against empty contours (blank alpha mask).
         # When RMBG produces an all-black mask, findContours returns [] and max() raises.
         # Fallback: return the full image bounding box so pipeline can continue.
-        if "empty_contours_guard" not in _ip_text:
-            _ip_text = _ip_path.read_text()
-            _ip_text = _ip_text.replace(
+        # NOTE: parameter is gray_image, not alpha.
+        _ip_text2 = _ip_path.read_text()
+        if "empty_contours_guard" not in _ip_text2:
+            _ip_text2 = _ip_text2.replace(
                 "    max_contour = max(contours, key=cv2.contourArea)",
                 "    if not contours:  # empty_contours_guard\n"
-                "        h, w = alpha.shape[:2]\n"
+                "        h, w = gray_image.shape[:2]\n"
                 "        return 0, 0, w, h\n"
                 "    max_contour = max(contours, key=cv2.contourArea)",
             )
-            _ip_path.write_text(_ip_text)
+            _ip_path.write_text(_ip_text2)
             print("[load_triposg] Patched image_process.py: empty contours guard")
 
     # Safety net: patch inference_utils.py to make diso import optional.