Internal error when an undefined section is used

[epage]

As I was trying to resolve my use case from #761, I assumed I could do sections=FUTURE,STDLIB,THIRDPARTY combined with the default section to get the behavior I wanted but I get an internal error

ERROR: Unrecoverable exception thrown when parsing /Users/edpage/src/trustedpath/ddi/bin/command_sync.py! This should NEVER happen.
If encountered, please open an issue: https://github.com/PyCQA/isort/issues/new
Traceback (most recent call last):
  File "/Users/edpage/.cache/ddi/venv_fmt/bin/isort", line 8, in <module>
    sys.exit(main())
  File "/Users/edpage/.cache/ddi/venv_fmt/lib/python3.8/site-packages/isort/main.py", line 953, in main
    for sort_attempt in attempt_iterator:
  File "/Users/edpage/.cache/ddi/venv_fmt/lib/python3.8/site-packages/isort/main.py", line 939, in <genexpr>
    sort_imports(  # type: ignore
  File "/Users/edpage/.cache/ddi/venv_fmt/lib/python3.8/site-packages/isort/main.py", line 95, in sort_imports
    incorrectly_sorted = not api.sort_file(
  File "/Users/edpage/.cache/ddi/venv_fmt/lib/python3.8/site-packages/isort/api.py", line 324, in sort_file
    changed = sort_stream(
  File "/Users/edpage/.cache/ddi/venv_fmt/lib/python3.8/site-packages/isort/api.py", line 158, in sort_stream
    changed = core.process(
  File "/Users/edpage/.cache/ddi/venv_fmt/lib/python3.8/site-packages/isort/core.py", line 332, in process
    parsed_content = parse.file_contents(import_section, config=config)
  File "/Users/edpage/.cache/ddi/venv_fmt/lib/python3.8/site-packages/isort/parse.py", line 527, in file_contents
    straight_import |= imports[placed_module][type_of_import].get(  # type: ignore
KeyError: 'FIRSTPARTY'

I've since found an alternative to what I was trying to accomplish but I figured it'd be good to raise awareness of this in case it sparked interest in resolving. Example resolutions include

• Unknown sections fall back to the default
• Provide a nicer user facing error to tell them what went wrong and clarify this in the docs.

This was with isort 5.6.4 in Python 3.8

[timothycrosley]

I agree! This error message is far from ideal, and better documentation overall would be very helpful here.
Thanks for raising this issue!

[ichard26]

Heya, it appears that this should be closed as PR #1572 has been merged. The PR author simply forgot that each issue you want to close automatically needs the keyword before it.

Fixes #1570 #1562

Just a triager of Black doing what they do best :-)