Today, I went to test.wikipedia.org (post train deployment), hit "Random page" and clicked the "Edit" tab. It didn't ask me what editor I wanted and started loading the VIsualEditor. It was taking a long time to load, so I hit the "Edit" tab again (which I know doesn't make sense). This caused it to become frozen on a full progress bar and throw 2 JS errors, both of which were:
TypeError: step is undefined
The error is semi-reproducible. Just click the Edit tab again during the middle of the VisualEditor loading process. Sometimes it will error, sometimes it won't. Seems to be timing related. [Only tested in Firefox.]
