Fix stack trace on custom ParserError

[kewisch]

I caught a ParserError with a weird stack, and it turns out the custom mangling we did before doesn't really cut it. With ES6+ we can simplify the instance variables.

I've only tested this in recent node and the firefox error console, both seem to contain a stack. The node stack even skips over the error class even without Error.captureStackTrace.

Does this look ok?

[coveralls]

Pull Request Test Coverage Report for Build 8687274538

Details

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.003%) to 98.031%

---

Totals
Change from base Build 8687196681:	-0.003%
Covered Lines:	9276
Relevant Lines:	9447

---

💛 - Coveralls

[darktrojan]

The JSDoc needs to be updated, but otherwise this seems okay to me.

[kewisch]

@darktrojan What would you like changed in the jsdoc? I think it is still accurate. I guess removing the @param so it rather inherits from Error maybe?

[darktrojan]

Yeah, that's what I had in mind. The @extends implies the @param. Today I am less convinced it matters. I'll approve the change and you can decide whether you want to keep it.