Allow custom errors to specify response HTTP codes

[crrobinson14]

Currently if you throw an error during any action, the response code is always 400. This change allows you to use the following pattern:

function NotFoundError(message, extraFields) {
    Error.call(this);

    this.name = this.constructor.name;
    this.message = message || '404: Not Found';
    this.responseHttpCode = 404;
    Object.assign(this, extraFields || {});
}

then in an action:

const { NotFoundError } = require('../../lib/customErrors');
...
const user = api.models.User.findByPk(userId);
if (!user) {
    throw new NotFoundError('Invalid userId');
}

This will result in a "Invalid userId" message passed back, with a responseHttpCode of 404 (not found). You can define as many error types as you want this way, e.g. using SessionError/AuthError for indicating 401/403 responses, ServerError for 5xx series errors (remote database failed), etc.

[evantahler]

Love the idea! Can you please add some tests for the new behavior?

[evantahler]

@crrobinson14 ping! Any update?

[evantahler]

... still waiting on some tests @crrobinson14 ...

[evantahler]

@piyushagwl007 This might be a great place to start after the tuotiral

[evantahler]

closing in favor of #1334