sounddevice.PortAudioError: Error opening InputStream: Invalid number of channels [PaErrorCode -9998]

[ssxcxS45XT]

I get the follow errer when I run sounddevice. Could anybody show me how to make it work?

My OS is Mac OS X 10.15.6.

$ cat main.py 
#!/usr/bin/env python3
# vim: set noexpandtab tabstop=2 shiftwidth=2 softtabstop=-1 fileencoding=utf-8:

import sounddevice
fs = 44100 
seconds = 10
myrecording = sounddevice.rec(int(seconds * fs), samplerate=fs, channels=2)

import wave
obj = wave.open('sound.wav', 'w')
obj.setnchannels(1)  # mono
obj.setsampwidth(2)
obj.setframerate(fs)
obj.writeframesraw(myrecording)
sounddevice.wait()
$ ./main.py 
Traceback (most recent call last):
  File "./main.py", line 7, in <module>
    myrecording = sounddevice.rec(int(seconds * fs), samplerate=fs, channels=2)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/sounddevice.py", line 275, in rec
    ctx.input_dtype, callback, blocking, **kwargs)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/sounddevice.py", line 2578, in start_stream
    **kwargs)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/sounddevice.py", line 1416, in __init__
    **_remove_self(locals()))
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/sounddevice.py", line 895, in __init__
    'Error opening {}'.format(self.__class__.__name__))
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/sounddevice.py", line 2738, in _check
    raise PortAudioError(errormsg, err)
sounddevice.PortAudioError: Error opening InputStream: Invalid number of channels [PaErrorCode -9998]

[mgeier]

Duplicate of #303?