It wouldnt be 'send to script', since that uses the script file in the send box.
What did you recently change?
Oh. Perhaps its triggering on world.save?
Yeah. Looks like its yelling at you because you don't have anything for your save script?
I guess. Game > Config > Scripts.
Then the save callback. Did you recently have one and then deleted it? Or have you recently put it in?
Yes, it's a bug. Thanks for reporting that. When I add new things like that I usually copy something similar (like the "world open" stuff) however I missed one place that zeroes out the despatch ID if the subroutine isn't used.
This will be fixed in version 3.61.
You could fix it for now by putting in a dummy "on world save" subroutine in your script file, and make it do nothing.