At the end of every green line (debug, show_next_waypoint) is a small biter, not moving:
Later it seems to no longer happen, will keep testing

All these biters are stationairy, they just stopped moving, and get killed by the lasers:

The bigger picture


(for some strange reason this save is 16 MB, while the same game, saved an hour later, is the "usual" 6 MB
https://www.dropbox.com/s/5uxs10wijoxt1 ... biters.zip