Help me please! What should I do if this error appears?

Need to know:
MC Launcher used?
Fabric Loader version?
Fabric API version?
Optifabric version?

Need to know: MC Launcher used? Fabric Loader version? Fabric API version? Optifabric version?

1. Im using a KLauncher (KLVoice 1.16.6. (
   it's built-in))

2-3-4. IDK

Need to know: MC Launcher used? Fabric Loader version? Fabric API version? Optifabric version?

1. Im using a KLauncher (KLVoice 1.16.6. (
   it's built-in))

2-3-4. IDK

That only answers the Launcher and its MC version but I need to know the rest of the mods as well in order to give you an informed resolution to your problem.

Need to know: MC Launcher used? Fabric Loader version? Fabric API version? Optifabric version?

1. Im using a KLauncher (KLVoice 1.16.6. (
   it's built-in))

2-3-4. IDK

Also it would help if you were using a legal minecraft launcher instead of a cracked launcher.