instruction renovation; allow manual keypoints at edit hands

app.py

@@ -314,7 +314,7 @@ def get_ref_anno(img, keypts):
             keypts[0] = np.array(keypts[0], dtype=np.float32)
         else:
             gr.Info("Number of right hand keypoints should be either 0 or 21.")
-            return None, None
+            return None, None, None
 
         if len(keypts[1]) == 0:
             keypts[1] = np.zeros((21, 2))
@@ -322,7 +322,7 @@ def get_ref_anno(img, keypts):
             keypts[1] = np.array(keypts[1], dtype=np.float32)
         else:
             gr.Info("Number of left hand keypoints should be either 0 or 21.")
-            return None, None
+            return None, None, None
 
         keypts = np.concatenate(keypts, axis=0)
     if REF_POSE_MASK: