Weird auth.js type behaviour with custom providers

I made a custom magic link email login provider for auth.js and it all works fine and dandy with no type errors to be seen; however, as soon as do a full app typecheck, while ignoring node modules on sveltekit, somehow the auth.js library types has anyone else ran to a similar issue? There is nothing inherently wrong with my ts config and my custom provider abides to the auth.js types for providers too.