Okay, so after some testing I’ve been able to pare this issue down to what I think is the bare minimum. Using end() in a trial with a MouseTracker before the MouseTracker is initialized causes the script to freeze with the error above in the JavaScript console. Here’s a much more minimal example that shows the problem (link same as before, https://farm.pcibex.net/r/BtxkDp/):
PennController.ResetPrefix(null) // Shorten command names (keep this line here)
Sequence('trial')
newTrial('trial',
newText('').log(), // this is just so there's a result to send, otherwise it spins forever
end(),
newMouseTracker('mouse') // comment out this line, or put it before end(), and it works
)
