There's another instance when the user can be logged out and the "Sign
in to continue" string doesn't appear on the page. Also report this as a
logged out error.

I tried catching the `argparse.ArgumentError` as described here, but
that didn't seem to work:
https://docs.python.org/3.9/library/argparse.html#exit-on-error

When I wrapped `args = argparser.parse_args()` in a `try` block, it
raised a `SystemExit` exception instead of `argparse.ArgumentError`.

Take inspiration from some of the suggestions in this Stack Overflow
answer:
https://stackoverflow.com/questions/5943249/python-argparse-and-controlling-overriding-the-exit-status-code

Since we just want to change the exit code, call
`argparse.ArgumentParser`'s `error()` method and exit with the error
code we want.

Rather than output a single tab to separate the extension name and
version, use `ljust` to create two visual columns.

I didn't realise that `re.match()` only matches starting at the
beginning of the string rather than matching anywhere inside it:
https://docs.python.org/3/library/re.html#re.match

Switch to `re.search()` to get the desired behaviour.