Custom errors for rules and global fallback

Hi @maticzav! First of all thanks for the awesome library!

I have few questions/suggestions about CustomErrors:

1. Is there a way to specify CustomError that will be returned from shield in case if permissions checks are failed?

Example: I have isAuthenticated rule

export default rule()((parent, args, { user }) => Boolean(user));

I want to return my custom 401 error like this

import { SevenBoom } from 'graphql-apollo-errors';

rule(null, { 
  customError: SevenBoom.unauthorized('You are not authenticated')
})((parent, args, { user }) => Boolean(user))

1. Is there a way to specify global CustomError instead of https://github.com/maticzav/graphql-shield/blob/master/src/index.ts#L234 which will be used in case if there is no rule specific error?

Example:

import { SevenBoom } from 'graphql-apollo-errors';

shield({ /* Rules… */ }, {
  customError: SevenBoom.forbidden('You are not allowed to do this action.')
})

I can implement this and looks like it is not a breaking change.

Just want to clarify if there is no way to do this in current version of the library?

Let me know if you have any questions. Thanks!

[blazestudios23]

Is there no way to just map error messages to rules? That seems like the way to go.

[reergymerej]

I’m a few years late, but this seems to be a general problem with functions doing more than one thing. Rules should just test and return a boolean. That’s a separate concern from deciding which error to throw.