[OptionsResolver] Changed order of validation

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | yes
| BC breaks?    | no (I don't think it causes breaks)
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #4500 (?)
| License       | MIT
| Doc PR        | -

It's both a new feature and bug fix actually... I let @fabpot decide on this one.

@sstok can you please confirm if this fixes #4500 ? I couldn't fully follow
that ticket and then I discovered this error. If not, can you please add more
information to your ticket about the problems?