Pausing print during initial heating causes undefined behavior
So I think I found the bug in the prusa firmware (3.9.1).
During initial heating, print can be paused and resumed.
However when heating is completed, extruder starts extruding material in whatever place it happens to be
and there is no movement on X, Y, or Z axis. Motors for X, Y and Z seem to be disabled and screen shows
that print is in progress.
This seem like an edge case that was not covered in the code. Probably routine for restarting the print expects the print to be fully started and if this assumption is not fulfilled, undefined behavior occurs.
I think this is undefined behavior because I remember that last time I did that this by accident, extruder carriage tried to move
outside the range of movement and when I tried to reproduce the problem it just started extruding in mid air without any movements.
I opened issue on github ( https://github.com/prusa3d/Prusa-Firmware/issues/2862 ) quite a while ago but no one responded so far so I decided to write about this here as well, hoping that someone maybe can look into this and confirm my finding.