[Feature Request] More helpful error message when single quotes detected

[agilgur5]

If you use single quotes, it will (confusingly) tell you "expected STRING, got undefined". Single quotes are in fact strings, but invalid JSON, and therefore a very common error (see #46 , and Kong/insomnia#1150), so I think a more informative error message would be much more helpful.

[prantlf]

You could add single quotes to the lexer and instead of recognising them as string declarators, you would just make the tokenisation fail. I did something similar for JavaScript-like comments, so that they could be either ignored, or reported by a better error message.

[agilgur5]

Oh cool, thanks for the suggestion @prantlf !

Good luck on the fork and hope it does well! I also maintain a heavily updated fork of a library :)