Hi all, When I updated to the latest version of prefect (0.13.17) one of my old scripts that built a docker storage fails mysteriously with the following message

---> Running in 26ae91f84100
Beginning health checks...
System Version check: OK
Cloudpickle serialization check: OK
Result check: OK
Environment dependency check: OK
All health checks passed.
Removing intermediate container 26ae91f84100
 ---> a63da9840884
Traceback (most recent call last):
  File "register.py", line 60, in <module>
    storage.build()
  File "/home/karteek/anaconda3/envs/prefect/lib/python3.6/site-packages/prefect/environments/storage/docker.py", line 359, in build
    self._build_image(push=push)
  File "/home/karteek/anaconda3/envs/prefect/lib/python3.6/site-packages/prefect/environments/storage/docker.py", line 423, in _build_image
    self._parse_generator_output(output)
  File "/home/karteek/anaconda3/envs/prefect/lib/python3.6/site-packages/prefect/environments/storage/docker.py", line 661, in _parse_generator_output
    or parsed.get("errorDetail", {}).get("message")
AttributeError: 'NoneType' object has no attribute 'strip'

Any thoughts on what might be happening here? I can confirm that the docker image is building without any issues and the logs show that all the health checks are passing. I am using python 3.6

Hi Karteek, that was a bug introduced in version 0.13.17, should be fixed in 0.13.18 (released yesterday).

Discussed here: https://prefect-community.slack.com/archives/CL09KU1K7/p1606481504407200