[PropertyAccessor] Allow null value for a array

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #12482
| License       | MIT
| Doc PR        | -
@boekkooi yeh, maybe nothing is wrong, but it's more readable when the formula is in brackets