`source_suffix` fallback doesn't allow `dict`

[mgeier]

This assumes that source_suffix is a list:

sphinx-autoapi/autoapi/extension.py

Line 162 in 613eff5

out_suffix = app.config.source_suffix[0]

Quite a long time ago, Sphinx added support for using a dict instead, and now this is the recommended usage, see https://www.sphinx-doc.org/en/master/usage/configuration.html#confval-source_suffix.

[ain-soph]

So maybe a quick fix would be list(source_suffix)[0] ?
and do any pre-checks to ensure that it won't be empty?

[mgeier]

AFAICT, the suffix is used later for reST files (the function name output_rst() makes me think that), so you should at least make sure that the suffix is actually appropriate for that format.

What if only non-reST suffixes are available in app.config.source_suffix?

I guess in this case you would maybe have to add something to the source suffixes?

[ain-soph]

Yes. It seems the repo authors don't take the case into consideration where ".rst" not in source_suffix.keys().

[AWhetter]

This was already closed in #321. Proper markdown support will be added in #287