The original error was that the client was missing ViaBackwards-5.0.4.jar, which can be found at
\Users[user]\AppData\Roaming.minecraft\libraries\com\mentalfrostbyte\ViaBackwards\5.0.4
The file was missing for me, probably not the case forr others, but you can get it from https://github.com/MarkGG8181/cloud/blob/main/sigma/ViaBackwards-5.0.4.jar
This fixed the crashing issue for me.
The original error was that the client was missing ViaBackwards-5.0.4.jar, which can be found at \Users[user]\AppData\Roaming.minecraft\libraries\com\mentalfrostbyte\ViaBackwards\5.0.4 The file was missing for me, probably not the case forr others, but you can get it from https://github.com/MarkGG8181/cloud/blob/main/sigma/ViaBackwards-5.0.4.jar This fixed the crashing issue for me.