After updating to current Fastload I got a crash, after removing every mod and just testing Fastload the crash below showed up.
Reverting back to Fastload+1.19.2-2.3.5 showed no errors
---- Minecraft Crash Report ----
// Why did you do that?

Time: 2022-11-22 18:58:12
Description: Initializing game

java.lang.RuntimeException: Mixin transformation of net.minecraft.class_3283 failed
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.getPostMixinClassByteArray(KnotClassDelegate.java:419)
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.tryLoadClass(KnotClassDelegate.java:323)
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.loadClass(KnotClassDelegate.java:218)
at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:145)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
at net.minecraft.class_310.(class_310.java:427)
at net.minecraft.client.main.Main.method_44604(Main.java:205)
at net.minecraft.client.main.Main.main(Main.java:51)
at net.fabricmc.loader.impl.game.minecraft.MinecraftGameProvider.launch(MinecraftGameProvider.java:461)
at net.fabricmc.loader.impl.launch.knot.Knot.launch(Knot.java:74)
at net.fabricmc.loader.impl.launch.knot.KnotClient.main(KnotClient.java:23)
Caused by: org.spongepowered.asm.mixin.transformer.throwables.MixinTransformerError: An unexpected critical error was encountered
at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:392)
at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClass(MixinTransformer.java:234)
at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClassBytes(MixinTransformer.java:202)
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.getPostMixinClassByteArray(KnotClassDelegate.java:414)
... 10 more
Caused by: org.spongepowered.asm.mixin.throwables.MixinApplyError: Mixin [fabric-resource-loader-v0.mixins.json:ResourcePackManagerMixin from mod fabric-resource-loader-v0] from phase [DEFAULT] in config [fabric-resource-loader-v0.mixins.json] FAILED during APPLY
at org.spongepowered.asm.mixin.transformer.MixinProcessor.handleMixinError(MixinProcessor.java:638)
at org.spongepowered.asm.mixin.transformer.MixinProcessor.handleMixinApplyError(MixinProcessor.java:589)
at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:379)
... 13 more
Caused by: org.spongepowered.asm.mixin.injection.throwables.InvalidInjectionException: Invalid descriptor on fabric-resource-loader-v0.mixins.json:ResourcePackManagerMixin from mod fabric-resource-loader-v0->@Inject::construct([Lnet/minecraft/class_3285;Lorg/spongepowered/asm/mixin/injection/callback/CallbackInfo;)V! Expected (Lnet/minecraft/class_3288$class_5351;[Lnet/minecraft/class_3285;Lorg/spongepowered/asm/mixin/injection/callback/CallbackInfo;)V but found ([Lnet/minecraft/class_3285;Lorg/spongepowered/asm/mixin/injection/callback/CallbackInfo;)V [INJECT Applicator Phase -> fabric-resource-loader-v0.mixins.json:ResourcePackManagerMixin from mod fabric-resource-loader-v0 -> Apply Injections -> -> Inject -> fabric-resource-loader-v0.mixins.json:ResourcePackManagerMixin from mod fabric-resource-loader-v0->@Inject::construct([Lnet/minecraft/class_3285;Lorg/spongepowered/asm/mixin/injection/callback/CallbackInfo;)V]
at org.spongepowered.asm.mixin.injection.callback.CallbackInjector.inject(CallbackInjector.java:567)
at org.spongepowered.asm.mixin.injection.callback.CallbackInjector.inject(CallbackInjector.java:497)
at org.spongepowered.asm.mixin.injection.code.Injector.inject(Injector.java:276)
at org.spongepowered.asm.mixin.injection.struct.InjectionInfo.inject(InjectionInfo.java:445)
at org.spongepowered.asm.mixin.transformer.MixinTargetContext.applyInjections(MixinTargetContext.java:1378)
at org.spongepowered.asm.mixin.transformer.MixinApplicatorStandard.applyInjections(MixinApplicatorStandard.java:1052)
at org.spongepowered.asm.mixin.transformer.MixinApplicatorStandard.applyMixin(MixinApplicatorStandard.java:400)
at org.spongepowered.asm.mixin.transformer.MixinApplicatorStandard.apply(MixinApplicatorStandard.java:325)
at org.spongepowered.asm.mixin.transformer.TargetClassContext.apply(TargetClassContext.java:421)
at org.spongepowered.asm.mixin.transformer.TargetClassContext.applyMixins(TargetClassContext.java:403)
at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:363)
... 13 more

Awesome! I'm glad it was solved.

Had the same problem, I updated some mods today and discovered through disabling one mod at a time that this one is the issue in the latest update

Being looked into. Will review the issue and look at the #35 for the possible fix. Apologies for any inconveniences

Should be fixed with the latest release. Will upload the changes to CF and Modrinth rn but there is already a release on GH if you can't wait for the upload times. Thanks for this!

I can confirm #35 fixed it.