Uncaught exception in thread "main"
java.lang.RuntimeException: Error creating Mixin config fabric-api-lookup-api-v1.mixins.json for mod fabric-api-lookup-api-v1
at net.fabricmc.loader.impl.launch.FabricMixinBootstrap.init(FabricMixinBootstrap.java:95)
at net.fabricmc.loader.impl.launch.knot.Knot.init(Knot.java:153)
at net.fabricmc.loader.impl.launch.knot.Knot.launch(Knot.java:68)
at net.fabricmc.loader.impl.launch.knot.KnotClient.main(KnotClient.java:23)
Caused by: org.spongepowered.asm.launch.MixinInitialisationError: Error initialising mixin config fabric-api-lookup-api-v1.mixins.json
at org.spongepowered.asm.mixin.transformer.Config.create(Config.java:153)
at org.spongepowered.asm.mixin.Mixins.createConfiguration(Mixins.java:100)
at org.spongepowered.asm.mixin.Mixins.addConfiguration(Mixins.java:87)
at net.fabricmc.loader.impl.launch.FabricMixinBootstrap.init(FabricMixinBootstrap.java:93)
... 3 more
Caused by: java.lang.IllegalArgumentException: The specified resource 'fabric-api-lookup-api-v1.mixins.json' was invalid or could not be read
at org.spongepowered.asm.mixin.transformer.MixinConfig.create(MixinConfig.java:1290)
at org.spongepowered.asm.mixin.transformer.Config.create(Config.java:148)
... 6 more

I didn't mess with anything in the mods, nor did i add any extra mods. I'm not entirely the smartest when it comes to running mods

And the error you got was....?

EDIT: Looking at the description of the modpack, it explicitly tells you that you don't need optifine for shaders

The modpack also appears to be for 1.16.5, which is not a version we support anymore, nor does the pack seem to include starlight by default.

1. You don't need Optifine for shaders
2. Optifine is extremely incompatible with our modpacks
3. This has literally nothing to do with Starlight

Closing this since the error isn't related to Starlight, as pointed out by chorbintime.