I do. It's an Android save file, is this still useful to you?

The savefile is the same. Sources are almost equal.

Savefile attached. Edit: watch out for the umber hulk lurking around the corner. My character doesn't have much in the form of reliable escape techniques yet.

I loaded the savefile into gdb in windows 15 times. I got a report of heap corruption once. 1020 bytes were allocated.

Three tries at loading it on macOS didn't turn up a problem. Setting a watchpoint on the address range for load.c's square_size might help diagnose this, if its value is overwritten by something after being assigned in rd_dungeon().

Thank you! I will try this. I can't reproduce the bug yet.

Similar for me in Linux. I got one crash on exiting the game for a double free, but I've also run several times with valgrind and got no memory issues at all.

tg122 - from the savefile you sent, can you say precisely what you do to get a crash?

I open the save file and immediately use a scroll of word of recall. Then it asks me which recall point I want to replace, and I select "Nowhere." Then while I'm waiting to be brought back to town, I kill the griffin, wear the metal cap that it drops. Then I kill the hippogryph, then an umber hulk attacks and I use a scroll of phase door. Then as soon as I get a message saying I'm being yanked homeward it crashes.
Edit: I just waited in place and all these monsters mentioned above came to me.

Hello, Nick! Please, can you tell us a little about quest system in FAangband ? I'm at level 30 of Amon Rudh now.. :)

There are 5 dungeon guardians at the bottom of dungeons (and Nan Dungortheb). The first two you kill will get you a new specialty ability. They're optional, but Morgoth has a "summon guardians" spell.