It's possible to have a controller without a default state in it

1. Create an animator controller and add a state machine to it
2. Add a couple of states inside the machine
3. There isn't any default state - which usually is prevented by assigning automatically a state to be the default one (for example after the default state is deleted, the next state is marked golden = default)
4. As soon as a state to the base layer is added, it's marked as default
5. Expected: first added state is marked as default - even if it's added inside a state machine