We're aware of this issue, and a fixed has been staged, but unfortunately the fix won't ship until next week since our systems are in lockdown for CS Ed week.
The problem is that there was supposed to be a check in bubble 11 that drawSeaStar used a loop -- the instructions in bubble 11 say to add one - but that check somehow got removed from bubble 11, but was carried through to bubbles 12 and beyond. Since the project is cumulative, every check from earlier bubbles is included in later bubbles.
If you go back to bubble 11 you can see that adding a loop to drawSeaStar is one of the ToDos. Unfortunately the check for it doesn't occur until bubble 12, which, yes, makes it confusing.
Sorry for the trouble ("bubble trouble"? )
Hope this helps