Returning a map in the parser instead of throwing exceptions

[alexschneider]

In our module.exports in our parser.coffee, we return a map that contains either an error or a program.

This unnecessarily complicates things, and we really ought to be throwing exceptions if we have errors - this returning an error and a result pattern is only really applicable for asynchronous code.

If consistency with the scanner is a big deal, we ought to push the program parsing onto the event loop and take in a callback that has an error and result argument like our scanner.

Also, we should consider making CustomError contain a stack trace to make debugging easier.

@rachelriv, is there any reason that the parser does this?

[rachelriv]

I just made it return a map containing the error since your previous implementation wasn't doing anything with errors and I wanted to ensure that they were at least being generated.

Throwing exceptions is fine but I was just focusing on finishing the parser first. If you want to throw exceptions, go for the implementation :smile:

However, I think we should focus on finishing the parser before doing anything too fancy with error handling.