I'm guessing that there is no way to show line numbers with this. That would be a great feature to add. Love it otherwise.
Topic on Extension talk:CodeMirror
@Z929669 Hello! In the Technical Wishes project at WMDE, we're planning to add line numbers to the syntax highlighting feature soon, probably in April 2021. More info: WMDE_Technical_Wishes/Line_Numbering
Best,
Johanna
Excellent. Thank you
@Z929669 Hi! Line numbers are now available for the template namespace on all wikis using CodeMirror. More namespaces will follow soon. Wishing you a good weekend,
Johanna