Fabric Loader Version: 0.14.8
OptiFabric Version: 1.13.10
Optifine Version: 1.19.1_HD_U_H9_pre1

Additional Mods:
- Baritone
- Aristois

https://pastebin.com/raw/vLcykd4f

Caused by: org.spongepowered.asm.mixin.throwables.MixinApplyError: Mixin [mixins.optifine.json:integration.MixinOptiFineFramebuffer from mod (unknown)] from phase [DEFAULT] in config [mixins.optifine.json] FAILED during APPLY
...
Caused by: org.spongepowered.asm.mixin.transformer.throwables.InvalidMixinException: @Shadow field stencilEnabled was not located in the target class net.minecraft.class_276. Using refmap mixins.emc.refmap.json

EMC's optifine integration seems to be outdated.
https://gitlab.com/EMC-Framework/EMC/-/blob/1.19.1/src/main/resources/mixins.optifine.json

How do I fix this?

EMC relies on optifine internal (not optifabric itself), so the optifabric developer can't deal with this.
I think you have three options:

1. ask the EMC developer to fix it
2. disable EMC (and mods requiring it - I think Aristois requires it)
3. disable optifabric and optifine