Can't load custom configuration with nesting via plugins/index.js

[jsdw]

Current behavior:

I would like to load some custom confiuration that's required across a bunch of tests (test user credentials for instance). To do this, I tried extending plugins/index.js to return the config I wanted. So, I modify plugins/index.js to return my nested config like so:

module.exports = (on, config) => {
  return { lark: { foo: 2 } }
}

But then when I try running Cypress I get the error (with stack trace):

Cannot set property 'foo' of undefined
TypeError: Cannot set property 'foo' of undefined
    at /Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/lib/config.js:300:37
    at /Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/node_modules/lodash/lodash.js:4905:15
    at baseForOwn (/Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/node_modules/lodash/lodash.js:2990:24)
    at /Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/node_modules/lodash/lodash.js:4874:18
    at Function.forEach (/Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/node_modules/lodash/lodash.js:9342:14)
    at setResolvedOn (/Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/lib/config.js:296:18)
    at /Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/lib/config.js:298:20
    at /Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/node_modules/lodash/lodash.js:4905:15
    at baseForOwn (/Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/node_modules/lodash/lodash.js:2990:24)
    at /Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/node_modules/lodash/lodash.js:4874:18
    at Function.forEach (/Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/node_modules/lodash/lodash.js:9342:14)
    at setResolvedOn (/Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/lib/config.js:296:18)
    at Object.updateWithPluginValues (/Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/lib/config.js:307:7)
    at /Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/lib/project.js:128:27
    at tryCatcher (/Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/node_modules/bluebird/js/release/util.js:16:23)
    at Promise._settlePromiseFromHandler (/Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/node_modules/bluebird/js/release/promise.js:510:31)
    at Promise._settlePromise (/Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/node_modules/bluebird/js/release/promise.js:567:18)
    at Promise._settlePromise0 (/Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/node_modules/bluebird/js/release/promise.js:612:10)
    at Promise._settlePromises (/Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/node_modules/bluebird/js/release/promise.js:691:18)
    at Async._drainQueue (/Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/node_modules/bluebird/js/release/async.js:133:16)
    at Async._drainQueues (/Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/node_modules/bluebird/js/release/async.js:143:10)
    at Immediate.Async.drainQueues (/Users/james.wilson/Library/Caches/Cypress/3.4.1/Cypress.app/Contents/Resources/app/packages/server/node_modules/bluebird/js/release/async.js:17:14)
    at runCallback (timers.js:789:20)
    at tryOnImmediate (timers.js:751:5)
    at processImmediate [as _immediateCallback] (timers.js:722:5)

When simplifying the case to be:

module.exports = (on, config) => {
  return { foo: 2 }
}

The config is loaded without issue.

Desired behavior:

I would expect/hope that I can return custom config with some degree of nesting in it, so that I can then use this config throughout the tests.

Steps to reproduce: (app code and test code)

From a new Cypress project, set the content of plugins/index.js to be:

module.exports = (on, config) => {
  return { lark: { foo: 2 } }
}

And then run

npx cypress run

Versions

Cypress package version: 3.4.1
Cypress binary version: 3.4.1

[jsdw]

Closing as it's a duplicate of #1736, which contains a workaround (woop!)