stop iteration if key pressed ONLY in a non headless mode

oi-sensor/oi-sensor.py

@@ -185,10 +185,10 @@ async def main():
             if not headless:
                 cv2.imshow("Frame", frame)
                 cv2.imshow("Mask", mask)
-
-            key = cv2.waitKey(1)
-            if key == 27:
-                break
+                # stop iteration if key pressed in a non headless mode
+                key = cv2.waitKey(1)
+                if key == 27:
+                    break
 
 if __name__ == "__main__":
     logging.basicConfig(level=logging.ERROR)