Error thrown when changing chapters

[shawnkendrick]

When a user toggles between chapters using the right and left arrow buttons, and error is thrown. Clicking the arrows does successfully change the chapter however. This is the error:

TypeError: Cannot read property 'length' of undefined
at app.bundle.js:31395
at Scope.$eval (angular.js:20985)
at Scope.$apply (angular.js:21088)
at updateStoryframesHandler (app.bundle.js:31386)
at callSubscriberWithDelayedExceptions (_collection.js:5)
at deliverMessage (_collection.js:37)
at deliverNamespaced (_collection.js:48)