Unable to load Diablo save game due to invalid monster animation

[AJenbo]

Discussed in #7508

On dlvl 7, there is an Illusion Weaver that is walking northeast, but its animation info is invalid (ticksPerFrame is zero). It's causing a divide-by-zero error when trying to convert the level.

https://github.com/user-attachments/files/17621051/Saves.zip

[StephenCWills]

The debugger stops on this line.

devilutionX/Source/loadsave.cpp

Line 1434 in 6318c55

offset = monster.position.CalculateWalkingOffset(monster.direction, monster.animInfo);

Ronb1238 said that the save was created in vanilla Diablo, and that he only downloaded DevilutionX to transfer the save to Hellfire. This is just speculation, but it could be that this is a vanilla edge case for invisible Hidden-type monsters that wouldn't occur in saves created by DevilutionX.