With the katex command-line interface I get this message:
LaTeX-incompatible input ...
In LaTeX, \\ or \newline does nothing in display mode [newLineInDisplayMode]
So… (a) don’t do that, and (b) we need to find a way to make that message visible.
See also: https://discourse.gohugo.io/t/katex-transform-tomath-throws-error-with-valid-syntax/53320/3
Related issues and pull requests: