What is the problem?
User is by the printer (Marlin), and see that something is wrong.
Stopping the print, would enable user to clean the bed, prepare for next print.
There is no way to tell OctoPrint to stop the job unless by a computer.
What is the best solution here ?
Maybe Marlin should have a menu item that causes an "Error: cancelled by user" ?
- or is there another "correct" way ?