Twitter 401s cause everyauth to crash

[jamesarosen]

To replicate:

1. set up everyauth with an express server and invalid Twitter credentials
2. go to /auth/twitter

What happens:

/private/tmp/meat.me/node_modules/everyauth/lib/modules/twitter.js:43
    return new Error(data.data.match(/<error>(.+)<\/error>/)[1]);
                                                            ^
TypeError: Cannot read property '1' of null
    at /private/tmp/meat.me/node_modules/everyauth/lib/modules/twitter.js:43:61
    at /private/tmp/meat.me/node_modules/everyauth/lib/step.js:97:21
    at [object Object].fail (/private/tmp/meat.me/node_modules/everyauth/lib/promise.js:53:24)

The problem is that Twitter is now returning data of the form

{
  "statusCode": 401,
  "data": "Failed to validate oauth signature and token"
}

Thus, data.data does not match /<error>(.+)<\/error>/ and that test returns null.

[nilya]

Also crash can be caused by promise.fail(err) in one of the steps.
For example if findOrCreateUser returns DB error everyauth crashes with

/project/node_modules/everyauth/lib/modules/google.js:47
    return new Error(data.data.match(/H1>(.+)<\/H1/)[1]);
                               ^
TypeError: Cannot call method 'match' of undefined
    at /project/node_modules/everyauth/lib/modules/google.js:47:32