Minecraft: 1.12.2
Forge: 14.23.5.2854

Report:
https://pastebin.com/Qw6X4rm9

Mods: 5
iceandfire-1.9.1-1.12.2
ImprovedMobs-1.12.2-1.6.9
jei_1.12.2-4.15.0.291
llibrary-1.7.19-1.12.2
TenshiLib-1.12.2-1.2.3

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In a modded survival world, I found a Ice & Fire Mausoleum Structure and upon getting close to it... the game crashed. I took another look but with only these listed mods installed and I was able to encounter the same crash.

Mausoleums have a chance of generating in Cold Biomes according to the wiki, although you can increase the chance inside Ice & Fire's config by lowering the number, by default it's 1800.

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