When I create a singleplayer world my game crashes. I load the game back up and the world is there but when I try to join my game just crashes again. Here is the crash report if it helps.

---- Minecraft Crash Report ----

WARNING: coremods are present:

  XaeroMinimapPlugin (Xaeros_Minimap_20.19.0_Forge_1.12.jar)

Contact their authors BEFORE contacting forge

// I let you down. Sorry :(

Time: 8/9/20 9:36 PM

Description: Exception in server tick loop

java.lang.NoSuchMethodError: net.minecraft.entity.EntityLiving$SpawnPlacementType.canSpawnAt(Lnet/minecraft/world/World;Lnet/minecraft/util/math/BlockPos;)Z

at net.minecraft.world.WorldEntitySpawner.func_180267_a(WorldEntitySpawner.java:226)

at net.minecraft.world.WorldEntitySpawner.func_77191_a(WorldEntitySpawner.java:282)

at net.minecraft.world.gen.ChunkGeneratorOverworld.func_185931_b(ChunkGeneratorOverworld.java:466)

at net.minecraft.world.chunk.Chunk.func_186034_a(Chunk.java:1019)

at net.minecraft.world.chunk.Chunk.func_186030_a(Chunk.java:999)

at net.minecraft.world.gen.ChunkProviderServer.func_186025_d(ChunkProviderServer.java:157)

at net.minecraft.server.MinecraftServer.func_71222_d(MinecraftServer.java:344)

at net.minecraft.server.integrated.IntegratedServer.func_71247_a(IntegratedServer.java:173)

at net.minecraft.server.integrated.IntegratedServer.func_71197_b(IntegratedServer.java:196)

at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:486)

at java.lang.Thread.run(Thread.java:745)

A detailed walkthrough of the error, its code path and all known details is as follows:

---------------------------------------------------------------------------------------

-- System Details --

Details:

Minecraft Version: 1.12.2

Operating System: Windows 10 (amd64) version 10.0

Java Version: 1.8.0_51, Oracle Corporation

Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation

Memory: 995008184 bytes (948 MB) / 2013265920 bytes (1920 MB) up to 3221225472 bytes (3072 MB)

JVM Flags: 8 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx3G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M

IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95

FML: MCP 9.42 Powered by Forge 14.23.5.2816 Optifine OptiFine_1.12.2_HD_U_C6 7 mods loaded, 7 mods active

States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored

| State  | ID                | Version         | Source                                | Signature                                |

|:------ |:----------------- |:--------------- |:------------------------------------- |:---------------------------------------- |

| LCHIJA | minecraft         | 1.12.2          | minecraft.jar                         | None                                     |

| LCHIJA | mcp               | 9.42            | minecraft.jar                         | None                                     |

| LCHIJA | FML               | 8.0.99.99       | forge-1.12.2-14.23.5.2816.jar         | e3c3d50c7c986df74c645c0ac54639741c90a557 |

| LCHIJA | forge             | 14.23.5.2816    | forge-1.12.2-14.23.5.2816.jar         | e3c3d50c7c986df74c645c0ac54639741c90a557 |

| LCHIJA | xaerominimap_core | 1.12.2-1.0      | minecraft.jar                         | None                                     |

| LCHIJA | thedalekmod       | (Update 58.1.0) | Dalek Mod - Update 58.1.jar           | None                                     |

| LCHIJA | xaerominimap      | 20.19.0         | Xaeros_Minimap_20.19.0_Forge_1.12.jar | None                                     |

Loaded coremods (and transformers): 

XaeroMinimapPlugin (Xaeros_Minimap_20.19.0_Forge_1.12.jar)

  xaero.common.core.transformer.ChunkTransformer

  xaero.common.core.transformer.NetHandlerPlayClientTransformer

  xaero.common.core.transformer.EntityPlayerTransformer

  xaero.common.core.transformer.AbstractClientPlayerTransformer

GL info: ~~ERROR~~ RuntimeException: No OpenGL context found in the current thread.

Profiler Position: N/A (disabled)

Player Count: 0 / 8; []

Type: Integrated Server (map_client.txt)

Is Modded: Definitely; Client brand changed to 'fml,forge'

Maybe a coremod problem.
Update forge to the latest 1.12.2 version

If that doesn't work, try removing mods such as optifine or xaero or updating those mods too.