[Bug] The GHFM previewer fails when its file extension is capitalised.

[roke-julian-lockhart]

When a CommonMark file's extension is capitalised, the renderer fails: ^{1 2}

Footnotes

1. #discussioncomment-15891619 ↩

2. #discussioncomment-16390159 ↩

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[roke-julian-lockhart]

See actions/stale/issues/719#issuecomment-1135116982.