Well, it was in fact a false alert, apparently unrelated to the script :) After a bit of investigation I removed every tile in the perimeter and discovered there were some hidden navigation paths overlapping the normal paths, but without being linked to any tile. My guess is these are some forgotten remnants of an old update you made months ago to fix some paths which were invisible or linked oddly, if I remember well. So back then, your update made visible most of these paths, but apparently I still have a few hidden things to fix here and there.
I managed to removed these floating paths by adding tiles at their level then removing all interaction between then. The strange thing is these paths were all "walk & interact", so they shouldn't have been a problem. But it doesn't matter, eveything works fine now :)