[FEAT] give errors from submit() exception

[sandhya-spend]

GS-8643

The exception thrown by form.submit() can also be used to populate errors on the fields.

Usage:

import {ValidationError} from 'mobx-autoform'
submit = (snapshot, form) => {
// `errors` is an object where the keys are the fields and the values are arrays of errors for the field.
const errors = {}
throw new ValidationError("Submission failed", errors)
}

[stellarhoof]

Looks like I was wrong. Command does support async functions, so you don't have to deal with Promise.resolve and catch.

Also, you can use

        if (err instanceof ValidationError) {
          state.errors = {
            '': [err.message],
            ...err.cause,
          }
        }

to use the error message as the message for the entire form.

[decrapifier]

	Warnings
⚠️	You should add at least 1 more reviewer to the PR

Coverage Report

👍 Test coverage is looking good.

Files	% Stmts	% Branch	% Funcs	% Lines	Uncovered Lines
src/futil.js	100	100	100	100		✅
src/index.js	100	96.61	96.67	100		✅
src/mobx.js	94.87	88.24	100	94.87	10, 11	✅

and 2 more...

Files	% Stmts	% Branch	% Funcs	% Lines	Uncovered Lines
src/util.js	100	100	100	100		✅
src/validators.js	52.38	100	50	52.38	6, 7, 8, 9, 10, 11, 12, 13, 14, 15	✅

Generated by 🚫 dangerJS against 65d4311

[stellarhoof]

Thanks @sandhya-spend. This is a nice improvement to our form library.