Re-implemented graphqlerrors package to be more idiomatic Go code.

[sogko]

Hi @chris-ramon

Really appreciate the work you've put into so far in making a golang graphql library thats closely based on graphql-js JS library released recently. (There are other golang-based graphql libraries but most of them were pre-graphql-js). Would love to see where this go.

I would like to make a suggestion for this library to be more Go-idiomatic, specifically with error-handling.
It'll make it easier to use it with other Go packages.

Comments appreciated.

Details

• Previous implementation requires package user to handle errors in non-idiomatic Go, e.g.:

    document, err := Parse(params)
    if err.Error != nil {
        // handle error
    }

Generally, most package users would expect a consistent error handling.

    // Parse() returns `error` interface
    document, err := Parse(params)
    if err != nil {
        // handle error
    }

This might seem trivial, but has an intangible benefit of not introducing more friction for other devs to adopt the packages.

Reference: https://github.com/golang/go/wiki/Errors

• Implemented other error types based on graphql-js
  • Added functions to create different types of GraphQLError (LocatedError, SynxtaxError)

Tested

Does not break existing tests.

$ go build
$ go test github.com/chris-ramon/graphql-go/language/parser github.com/chris-ramon/graphql-go/language/lexer
ok      github.com/chris-ramon/graphql-go/language/parser   0.005s
ok      github.com/chris-ramon/graphql-go/language/lexer    0.008s

[chris-ramon]

Wow! 🌟 thanks for your contribution @sogko !

This is definitely something need to be improved! and I totally agree with what you had done. 👍

What do you think about having shorter file naming for files within pkg errors, so instead of having formatted_error.go we just have formatted.go and so on.

[sogko]

Hi @chris-ramon,

Thanks for taking time to look at this PR, appreciate the effort 👍🏻

Yeah I agree with you, it could be less verbose lol. I've updated the PR with those changes.

Btw, I've been working on the parser on another branch with the goal of passing graphql-js parser tests.
I'll make a separate PR when its ready.