I'm not quite sure what is causing this and I don't know if anyone else is experiencing this, but according to the launcher, "The game crashed whilst initializing game. Error: java.lang.RuntimeException: Could not execute entrypoint stage 'main' due to errors, provided by 'more_armor_trims'!"

Can you provide more context? (other mods you have installed, version of Minecraft and mod, actions that could have caused the crash)