Shows BrokenPipeError while writing frames

When I finished downloading everything, I tried to render the example scene on my mac, but it showed an error. Below is the terminal message:
```bash
(base) situjianfeideMacBook-Air:manim situjianfei$ manim example_scenes.py SquareToCircle

Media will be written to ./media/. You can change this behavior with the --media_dir flag.
Traceback (most recent call last):
File "/Users/situjianfei/Anaconda/anaconda3/lib/python3.7/site-packages/manimlib/extract_scene.py", line 155, in main
scene = SceneClass(**scene_kwargs)
File "/Users/situjianfei/Anaconda/anaconda3/lib/python3.7/site-packages/manimlib/scene/scene.py", line 53, in __init__
self.construct()
File "example_scenes.py", line 83, in construct
self.play(ShowCreation(square))
File "/Users/situjianfei/Anaconda/anaconda3/lib/python3.7/site-packages/manimlib/scene/scene.py", line 406, in wrapper
func(self, *args, **kwargs)
File "/Users/situjianfei/Anaconda/anaconda3/lib/python3.7/site-packages/manimlib/scene/scene.py", line 463, in play
self.progress_through_animations(animations)
File "/Users/situjianfei/Anaconda/anaconda3/lib/python3.7/site-packages/manimlib/scene/scene.py", line 439, in progress_through_animations
self.add_frames(self.get_frame())
File "/Users/situjianfei/Anaconda/anaconda3/lib/python3.7/site-packages/manimlib/scene/scene.py", line 543, in add_frames
self.file_writer.write_frame(frame)
File "/Users/situjianfei/Anaconda/anaconda3/lib/python3.7/site-packages/manimlib/scene/scene_file_writer.py", line 185, in write_frame
self.writing_process.stdin.write(frame.tostring())
BrokenPipeError: [Errno 32] Broken pipe

(base) situjianfeideMacBook-Air:manim situjianfei$
```