Minecraft 1.18.2
Better Furnaces Reforged 1.3.0
Forge 40.1.74

World crashes when using Diamond Furnace while Project MMO is installed and can no longer be opened

Thread: Server thread
Stacktrace:
at wily.betterfurnaces.blockentity.AbstractSmeltingBlockEntity.smeltItem(AbstractSmeltingBlockEntity.java:857) ~[BetterFurnacesReforged-1.18.2-1.2.8.jar%2398!/:1.18.2-1.2.8] {re:classloading}
at wily.betterfurnaces.blockentity.AbstractSmeltingBlockEntity.trySmelt(AbstractSmeltingBlockEntity.java:367) ~[BetterFurnacesReforged-1.18.2-1.2.8.jar%2398!/:1.18.2-1.2.8] {re:classloading}
at wily.betterfurnaces.blockentity.AbstractSmeltingBlockEntity.tick(AbstractSmeltingBlockEntity.java:566) ~[BetterFurnacesReforged-1.18.2-1.2.8.jar%2398!/:1.18.2-1.2.8] {re:classloading}
at net.minecraft.world.level.chunk.LevelChunk$BoundTickingBlockEntity.m_142224_(LevelChunk.java:673) ~[client-1.18.2-20220404.173914-srg.jar%23403!/:?] {re:classloading}
at net.minecraft.world.level.chunk.LevelChunk$RebindableTickingBlockEntityWrapper.m_142224_(LevelChunk.java:766) ~[client-1.18.2-20220404.173914-srg.jar%23403!/:?] {re:classloading}
at net.minecraft.world.level.Level.m_46463_(Level.java:476) ~[client-1.18.2-20220404.173914-srg.jar%23403!/:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,pl:mixin:APP:dynamiclightsreforged.mixins.json:WorldMixin,pl:mixin:APP:radium.mixins.json:alloc.chunk_random.WorldMixin,pl:mixin:APP:radium.mixins.json:world.block_entity_retrieval.WorldMixin,pl:mixin:APP:radium.mixins.json:world.chunk_access.WorldMixin,pl:mixin:APP:radium.mixins.json:world.inline_block_access.WorldMixin,pl:mixin:APP:radium.mixins.json:world.inline_height.WorldMixin,pl:mixin:APP:lootr.mixins.json:MixinLevel,pl:mixin:APP:enhancedcelestials.mixins.json:MixinWorld,pl:mixin:A}
at net.minecraft.server.level.ServerLevel.m_8793_(ServerLevel.java:327) ~[client-1.18.2-20220404.173914-srg.jar%23403!/:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,pl:mixin:APP:supplementaries.mixins.json:ServerLevelMixin,pl:mixin:APP:the_bumblezone.mixins.json:world.ServerWorldMixin,pl:mixin:APP:radium.mixins.json:ai.nearby_entity_tracking.ServerWorldAccessor,pl:mixin:APP:radium.mixins.json:alloc.chunk_random.ServerWorldMixin,pl:mixin:APP:radium.mixins.json:chunk.entity_class_groups.ServerWorldAccessor,pl:mixin:APP:radium.mixins.json:entity.inactive_navigations.ServerWorldMixin,pl:mixin:APP:radium.mixins.json:profiler.ServerWorldMixin,pl:mixin:APP:immersiveengineering.mixins.json:coremods.ServerWorldMixin,pl:mixin:APP:simplerpc.mixins.json:ServerWorldMixin,pl:mixin:APP:betterdeserttemples.mixins.json:ServerLevelMixin,pl:mixin:APP:blueprint.mixins.json:ServerLevelMixin,pl:mixin:APP:enhancedcelestials.mixins.json:MixinServerWorld,pl:mixin:APP:create.mixins.json:accessor.ServerLevelAccessor,pl:mixin:A}
-- Block entity being ticked --
Details:
Name: betterfurnacesreforged:diamond_furnace // wily.betterfurnaces.blockentity.DiamondFurnaceBlockEntity
Block: Block{betterfurnacesreforged:diamond_furnace}[colored=false,facing=north,lit=true,type=0]
Block location: World: (97,63,109), Section: (at 1,15,13 in 6,3,6; chunk contains blocks 96,-64,96 to 111,319,111), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,-64,0 to 511,319,511)
Block: Block{betterfurnacesreforged:diamond_furnace}[colored=false,facing=north,lit=true,type=0]
Block location: World: (97,63,109), Section: (at 1,15,13 in 6,3,6; chunk contains blocks 96,-64,96 to 111,319,111), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,-64,0 to 511,319,511)
Stacktrace:
at net.minecraft.world.level.chunk.LevelChunk$BoundTickingBlockEntity.m_142224_(LevelChunk.java:673) ~[client-1.18.2-20220404.173914-srg.jar%23403!/:?] {re:classloading}
at net.minecraft.world.level.chunk.LevelChunk$RebindableTickingBlockEntityWrapper.m_142224_(LevelChunk.java:766) ~[client-1.18.2-20220404.173914-srg.jar%23403!/:?] {re:classloading}
at net.minecraft.world.level.Level.m_46463_(Level.java:476) ~[client-1.18.2-20220404.173914-srg.jar%23403!/:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,pl:mixin:APP:dynamiclightsreforged.mixins.json:WorldMixin,pl:mixin:APP:radium.mixins.json:alloc.chunk_random.WorldMixin,pl:mixin:APP:radium.mixins.json:world.block_entity_retrieval.WorldMixin,pl:mixin:APP:radium.mixins.json:world.chunk_access.WorldMixin,pl:mixin:APP:radium.mixins.json:world.inline_block_access.WorldMixin,pl:mixin:APP:radium.mixins.json:world.inline_height.WorldMixin,pl:mixin:APP:lootr.mixins.json:MixinLevel,pl:mixin:APP:enhancedcelestials.mixins.json:MixinWorld,pl:mixin:A}
at net.minecraft.server.level.ServerLevel.m_8793_(ServerLevel.java:327) ~[client-1.18.2-20220404.173914-srg.jar%23403!/:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,pl:mixin:APP:supplementaries.mixins.json:ServerLevelMixin,pl:mixin:APP:the_bumblezone.mixins.json:world.ServerWorldMixin,pl:mixin:APP:radium.mixins.json:ai.nearby_entity_tracking.ServerWorldAccessor,pl:mixin:APP:radium.mixins.json:alloc.chunk_random.ServerWorldMixin,pl:mixin:APP:radium.mixins.json:chunk.entity_class_groups.ServerWorldAccessor,pl:mixin:APP:radium.mixins.json:entity.inactive_navigations.ServerWorldMixin,pl:mixin:APP:radium.mixins.json:profiler.ServerWorldMixin,pl:mixin:APP:immersiveengineering.mixins.json:coremods.ServerWorldMixin,pl:mixin:APP:simplerpc.mixins.json:ServerWorldMixin,pl:mixin:APP:betterdeserttemples.mixins.json:ServerLevelMixin,pl:mixin:APP:blueprint.mixins.json:ServerLevelMixin,pl:mixin:APP:enhancedcelestials.mixins.json:MixinServerWorld,pl:mixin:APP:create.mixins.json:accessor.ServerLevelAccessor,pl:mixin:A}
at net.minecraft.server.MinecraftServer.m_5703_(MinecraftServer.java:902) ~[client-1.18.2-20220404.173914-srg.jar%23403!/:?] {re:mixin,pl:accesstransformer:B,xf:fml:openpartiesandclaims:xaero_pac_minecraftserverclass,re:classloading,pl:accesstransformer:B,xf:fml:openpartiesandclaims:xaero_pac_minecraftserverclass,pl:mixin:A}
at net.minecraft.server.MinecraftServer.m_5705_(MinecraftServer.java:842) ~[client-1.18.2-20220404.173914-srg.jar%23403!/:?] {re:mixin,pl:accesstransformer:B,xf:fml:openpartiesandclaims:xaero_pac_minecraftserverclass,re:classloading,pl:accesstransformer:B,xf:fml:openpartiesandclaims:xaero_pac_minecraftserverclass,pl:mixin:A}
at net.minecraft.client.server.IntegratedServer.m_5705_(IntegratedServer.java:84) ~[client-1.18.2-20220404.173914-srg.jar%23403!/:?] {re:classloading,xf:fml:openpartiesandclaims:xaero_pac_integratedserver_tickpaused,pl:runtimedistcleaner:A,re:mixin,xf:fml:openpartiesandclaims:xaero_pac_integratedserver_tickpaused,pl:runtimedistcleaner:A}
at net.minecraft.server.MinecraftServer.m_130011_(MinecraftServer.java:685) ~[client-1.18.2-20220404.173914-srg.jar%23403!/:?] {re:mixin,pl:accesstransformer:B,xf:fml:openpartiesandclaims:xaero_pac_minecraftserverclass,re:classloading,pl:accesstransformer:B,xf:fml:openpartiesandclaims:xaero_pac_minecraftserverclass,pl:mixin:A}
at net.minecraft.server.MinecraftServer.m_177918_(MinecraftServer.java:261) ~[client-1.18.2-20220404.173914-srg.jar%23403!/:?] {re:mixin,pl:accesstransformer:B,xf:fml:openpartiesandclaims:xaero_pac_minecraftserverclass,re:classloading,pl:accesstransformer:B,xf:fml:openpartiesandclaims:xaero_pac_minecraftserverclass,pl:mixin:A}
at java.lang.Thread.run(Thread.java:833) [?:?] {re:mixin}

You certainly downloaded an outdated version of Project MMO, I tested it with the latest version of the mod and it works perfectly

No, I'm using the most recent version of PMMO for 1.18.2, version 2.0.0.10, released August 9, 2022.

Sorry to inform you, go to curseforge, this is an alpha version of 1.18.2, the current one is this https://www.curseforge.com/minecraft/mc-mods/project-mmo/files/3809102

Version 2.0.0.10 is unstable because it is alpha and therefore unsupported

Of course this was due to changes in Project MMO API during the development of Better Furnaces Reforged, which was not updated, I will check this crash and post the fix soon.