There's an annoying bug where, if you're building off the word the train is currently travelling on, it marks the prior word as invalid, so you can't continue b

There's an annoying bug where, if you're building off the word the train is currently travelling on, it marks the prior word as invalid, so you can't continue building your extension (even if the train hasn't reached your intersection point yet). This means you auto-fail if the train reaches the current latest word while you're working on the next one.