Seems like some kind of compatibility issue when using Optifabric/Optifine. Having Optifabric/Optifine disabled works when Enhanced Celestials is enabled, but will crash if both mods are enabled.

Using Enhanced Celestials 2.0.2 for Fabric.

crash-2021-08-22_00.52.57-client.txt

you're using it on 1.17
enhanced celestials is for up to 1.16

also it's a forge mod, not fabric

There is a fabric version here.

you're using it on 1.17
enhanced celestials is for up to 1.16

also it's a forge mod, not fabric

both forge + fabric

Seems like some kind of compatibility issue when using Optifabric/Optifine. Having Optifabric/Optifine disabled works when Enhanced Celestials is enabled, but will crash if both mods are enabled.

Using Enhanced Celestials 2.0.2 for Fabric.

crash-2021-08-22_00.52.57-client.txt

sadly i dont run the optifabric mod, you'll need to report it to them if it hasnt already been fixed