Extraneous names for current state type

[Pumpuli]

A machine's current property type ends up containing extra property names.

const machine = createMachine({
    a: state(),
    b: state()
});

type Foo = typeof machine['current'];
// Expected:
// type Foo = 'a' | 'b';
// Actual:
// type Foo = 'a' | 'b' | keyof MachineState<string>;
// (Expands to):
// type Foo = 'a' | 'b' | 'final' | 'transitions' | 'immediate' | 'enter';

I believe this is caused by the change to createMachine() type in 4f6fb69. Even though the third type argument to Machine in the return value is unchanged: AllStateKeys<S>, the type of S was changed. Now S is a full MachineStates object, whose values are objects with keys final, transitions, immediate and enter. So when passing a full MachineState to AllStateKeys, it extracts nested keys too. Thus the result is all the state keys plus the nested final, transitions, immediate and enter.

[matthewp]

Thanks for the catch, do you think you could submit a PR to fix?