TypeError: expected string or bytes-like object in onionoo monitoring script

I suddenly get a bunch of

Traceback (most recent call last):
  File "/srv/onionoo.torproject.org/onionoo/monitoring/network/onionoo", line 206, in <module>
    version = "{}".format(re.sub('\W+', '_', bridge.get('version')))
  File "/usr/lib/python3.7/re.py", line 192, in sub
    return _compile(pattern, flags).sub(repl, string, count)
TypeError: expected string or bytes-like object

errors.