So, the game crashes on startup with the following mods:

Fabric API
Haema
Fabric Language Kotlin

The crash indicates something related to Bewitchment - which I'm unsure if it is required, or if it is similar to Origins and can interact with Haema that way. Either way, the crash is consistent on the latest Fabric version and API.

[16:39:18] [main/INFO]: Loading for game Minecraft 1.17.1
[16:39:18] [main/WARN]: Warnings were found!

• Conflicting versions found for fabric-api-base: used 0.3.0+a02b44633d, also found 0.3.0+a02b4463d5, 0.3.0+a02b446318
• Conflicting versions found for fabric-screen-api-v1: used 1.0.4+155f865c18, also found 1.0.4+198a96213d
  [16:39:18] [main/INFO]: [FabricLoader] Loading 69 mods:
  • [email protected]
  • [email protected]
  • [email protected]
  • [email protected]
  • [email protected]+1.17
  • [email protected]+a02b44633d
  • [email protected]+2f75c6ce18
  • [email protected]+b06cb95b18
  • [email protected]+a02b446318
  • [email protected]+5ab9934c18
  • [email protected]+92519afa18
  • [email protected]+a02b446318
  • [email protected]+211ddf9518
  • [email protected]+be9da31018
  • [email protected]+6cefd57718
  • [email protected]+62e33f4118
  • [email protected]+a722d8c018
  • [email protected]+92519afa18
  • [email protected]+6cefd57718
    - [email protected]+a02b446318
    - [email protected]+b7ab612118
    - [email protected]+a02b446318
    - [email protected]+36b77c3e18
    - [email protected]+kotlin.1.5.30
    - [email protected]+a02b446318
    - [email protected]+a02b446318
    - [email protected]+92519afa18
    - [email protected]+a02b446318
    - [email protected]+2e8bd82f18
    - [email protected]+a02b446318
    - [email protected]+92519afa18
    - [email protected]+b7ab612118
    - [email protected]+a02b446318
    - [email protected]+a02b446318
    - [email protected]
    - [email protected]+e2961fee18
    - [email protected]+5f02c96918
    - [email protected]+a02b446318
    - [email protected]+b06cb95b18
    - [email protected]+a02b446318
    - [email protected]+a02b446318
    - [email protected]+92519afa18
    - [email protected]+b06cb95b18
    - [email protected]+a00e834b18
    - [email protected]+155f865c18
    - [email protected]+a02b446318
    - [email protected]+5ab9934c18
    - [email protected]+b06cb95b18
    - [email protected]+a02b446318
    - [email protected]+b7ab612118
    - [email protected]+96bf6a7e18
    - [email protected]
    - [email protected]
    - [email protected]+1.17
    - java@16
    - [email protected]
    - [email protected]
    - [email protected]
    - [email protected]
    - [email protected]
    - [email protected]
    - [email protected]
    - [email protected]
    - [email protected]
    - [email protected]
    - [email protected]
    - [email protected]
    - [email protected]
    - [email protected]
    [16:39:20] [main/INFO]: SpongePowered MIXIN Subsystem Version=0.8.2 Source=file:/C:/Users/John/Desktop/MultiMC/libraries/net/fabricmc/sponge-mixin/0.9.4+mixin.0.8.2/sponge-mixin-0.9.4+mixin.0.8.2.jar Service=Knot/Fabric Env=CLIENT
    [16:39:20] [main/INFO]: Compatibility level set to JAVA_16
    [16:39:21] [main/WARN]: Error loading class: moriyashiine/bewitchment/common/registry/BWDamageSources (java.lang.ClassNotFoundException: moriyashiine/bewitchment/common/registry/BWDamageSources)
    [16:39:21] [main/WARN]: @mixin target moriyashiine.bewitchment.common.registry.BWDamageSources was not found haema_compat.mixins.json:bewitchment.BWDamageSourcesMixin
    [16:39:21] [main/WARN]: Error loading class: moriyashiine/bewitchment/common/entity/living/VampireEntity (java.lang.ClassNotFoundException: moriyashiine/bewitchment/common/entity/living/VampireEntity)
    [16:39:21] [main/WARN]: @mixin target moriyashiine.bewitchment.common.entity.living.VampireEntity was not found haema_compat.mixins.json:bewitchment.VampireEntityMixin
    [16:39:21] [main/WARN]: Error loading class: ladysnake/ratsmischief/common/entity/RatEntity (java.lang.ClassNotFoundException: ladysnake/ratsmischief/common/entity/RatEntity)
    [16:39:21] [main/WARN]: @mixin target ladysnake.ratsmischief.common.entity.RatEntity was not found haema_compat.mixins.json:rats.RatEntityMixin
    [16:39:21] [main/WARN]: Error loading class: ladysnake/ratsmischief/client/model/RatEntityModel (java.lang.ClassNotFoundException: ladysnake/ratsmischief/client/model/RatEntityModel)
    [16:39:21] [main/WARN]: @mixin target ladysnake.ratsmischief.client.model.RatEntityModel was not found haema_compat.mixins.json:rats.client.RatEntityModelMixin
    [16:39:21] [main/WARN]: @mixin target net/minecraft/class_2474$class_5124 is public in fabric-tag-extensions-v0.mixins.json:MixinObjectBuilder and should be specified in value
    [16:39:22] [main/WARN]: @reDIrect conflict. Skipping somnus.mixins.json:MixinPlayerEntity->@reDIrect::somnus$isDay(Lnet/minecraft/class_1937;)Z with priority 1000, already redirected by fabric-entity-events-v1.mixins.json:PlayerEntityMixin->@reDIrect::redirectDaySleepCheck(Lnet/minecraft/class_1937;)Z with priority 1000
    [16:39:23] [main/WARN]: @reDIrect conflict. Skipping somnus.mixins.json:MixinPlayerEntity->@reDIrect::somnus$isDay(Lnet/minecraft/class_1937;)Z with priority 1000, already redirected by fabric-entity-events-v1.mixins.json:PlayerEntityMixin->@reDIrect::redirectDaySleepCheck(Lnet/minecraft/class_1937;)Z with priority 1000

The issue is that fabric api has had an update which makes it incompatible with somnus api. I'll release an update to haema to make it not use somnus api.