Essentially what the title says.
It says:

The game crashed whilst mouseclicked event handler
Error: java.lang.RuntimeException: Mixin transformation of net.minecraft.class_446 failed
Exit Code: -1

And the crash report is attached
crash-2022-07-09_17.14.01-client.txt

Likely duplicate of #42 and #43; please report this issue to Optifabric instead.