What should happen to disposed targets when the block is running as a promise?

[apple502j]

Title explains most stuff.

There are several promise blocks that delay the execution of the block (instead of using it as a substitute for util.yield or requestRedraw):

• say/think for secs
• ask and wait
• start sound until done
• TTS
• peripheral blocks

Luckily, none of the blocks crash if the target is disposed while the block is running as a promise. However, this is easy to introduce (Scratch Labs has this issue with zoom effect + text extension) so there should be some sort of ways to handle this condition easily.

[ericrosenbaum]

Thanks for noting the bug in Scratch Lab- I've filed that one in the Scratch Lab repo