I couldn't reproduce the crash, but the map was fairly corrupt. A fixed one is attached: two 2-walled sectors were deleted.
(This was done by listing all corruptions with "corruptcheck now" from the console, then finding the right ones with Alt+"]" and finally deleting each affected sector by highlighting it and pressing Ctrl+LShift+DEL.)
edit: OK, taking a second look at the map, it's easy to see why the crash happened. Take sector 289: its .nextwall is 2080, but its .nextsector is
-134. Much code assumes that ".nextsector >= 0
iff .nextwall >= 0", so it's expected to cause problems. The reason why Mapster32 didn't report this particular (much worse) problem is because the wall in question already had another inconsistency, and the editor doesn't report multiple corruptions of the same sector or wall to not spam the log too much.
The bottom line: corruptions from level 3 on, but especially from level 4 on, are very serious.