[OptionsResolver] fix count() and exceptions

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Please see commits.
All these methods should actually not be reachable. Having a specific message makes people think, there are other methods that are valid from a closure. Also it increases maintanance. I even thought about making this the default message in the constructor of access exception.