When adapting Zizzo's zone entry locations code for Veins (it has debug messages printed to log), I think I have ran into a probable cause of the bug. Further testing confirmed it (I used the static map in this testing to shorten the log, see http://forums.te4.org/viewtopic.php?f=36&t=42266)
Used breaking edge Veins, which can be easily gotten from Git via download zip button if more testing is needed.
Sequence of events: go up to worldmap, find other stairs down (remember the locations are random every new game), go down, debug zone back to Veins of the Earth [because I was stupid and forgot to place stairs up in Arena], go down, debug zone back, watch game break.
Look for
in te4log (lines 2763 [game start], 2823 [go up], 2915 [go down], 2958 [debug back], 3036 [go down] ....[GAME] changeLevel
Line 3072
should be followed by another [GAME] changeLevel, but is not, and this is where the game breaks (no player on map, quit game)No zone events loaded
(1030, 1083 are from an older game)
Log attached.
>Tl'dr: Worldmap bug is caused by changeLevel code (the part where it calls game.player:move) not firing. No idea why.