Trying to run `wget https://raw.githubusercontent.com/KDE/craft/master/setup/CraftBootstrap.py -O CraftSetup.py && echo 0 | python3.6 CraftSetup.py --prefix ~/CraftRoot` on the Docker image `ubuntu:18.04` fails due to

    oot/CraftRoot) craft craft: 0 secondsjoin() argument must be str or bytes, not 'NoneType'
    Traceback (most recent call last):
      File "/root/CraftRoot/craft-master/bin/craft.py", line 254, in <module>
        success = main()
      File "/root/CraftRoot/craft-master/bin/craft.py", line 187, in main
        helper.setupEnvironment()
      File "/root/CraftRoot/craft-master/bin/CraftSetupHelper.py", line 301, in setupEnvironment
        self.setXDG()
      File "/root/CraftRoot/craft-master/bin/CraftSetupHelper.py", line 233, in setXDG
        os.path.join(CraftStandardDirs.craftRoot(), "home", os.getenv("USER"), ".local5", "share"))
      File "/usr/lib/python3.6/posixpath.py", line 94, in join
        genericpath._check_arg_types('join', a, *p)
      File "/usr/lib/python3.6/genericpath.py", line 149, in _check_arg_types
        (funcname, s.__class__.__name__)) from None
    TypeError: join() argument must be str or bytes, not 'NoneType'

    Execute: /usr/bin/python3.6 /root/CraftRoot/craft-master/bin/craft.py craft

The complete output and command chain can be inspected at https://gitlab.com/krichter/craft/-/jobs/78554991.

The official Ubuntu Docker images are pretty bare systems, however the user shouldn't be left in any situation without feedback.

Solving https://bugs.kde.org/show_bug.cgi?id=396030 might avoid this issue, however it indicates that an exception case isn't handled well and should be dealt with nonetheless.

experienced with v1.3-5775-g5c4193223