Update app.py

app.py

@@ -107,7 +107,7 @@ def infer(image_in):
                 cv2.circle(img, arrow_tip, 3, (0, 0, 255), cv2.FILLED)
                 arrow_tail = find_tail(approx[:,0,:], arrow_tip)
                 if arrow_tail :
-                    arrows_coordinates.append([arrow_tail, arrow_tip])
+                    arrows_coordinates.append([list(arrow_tail), list(arrow_tip)])
                     cv2.circle(img, arrow_tail, 3, (255, 0, 0), cv2.FILLED)
                     # Calculate length and angle
                     arrow_length = get_length(arrow_tip, arrow_tail)