Make it possible to disable provider check errors

[Quernest]

Perhaps the best answer is to:

1. Have a fallback (destructing is nice)
2. export the fallback modal (so that my usecase can do an === compare and disable).
3. Move the exception to the fallback functions.

This would

1. Allow the existing API.
2. Fail fast for people who don't do an explicit check
3. Allow for no provider detection (my usecase)

const modal = useModal();
if (modal === FallbackModal) {
  // disable
} else { 
  const { showModal } = modal;
  // showmaol
}

Originally posted by @michaeltford in #84 (comment)