You had errors in your syntax. Use --help for further information.

[ssbarnea]

The You had errors in your syntax. Use --help for further information. does not give any kind of feedback regarding what was wrong with the syntax.

Enabling the -v does not help at all, nor does the recommended --help option.

[knsv]

The same root cause as in the editor I guess. I comes down to the feedback from the parse. Will think a bit on how this could be improved.

[StingyJack]

I get this when forgetting to double-dash long name options, like
-svg
instead of
--svg

[tylerlong]

Paste your code to https://mermaidjs.github.io/mermaid-live-editor/ and you can get real time information about syntax errors.