$this of type Osnova\Services\Subsites\Traits\SubsitesService is incompatible with the type Osnova\OsnovaResource|null expected by parameter $resource of Osnova\Services\Subsites\Subsites::getSubsite().
(
Ignorable by Annotation
)
If this is a false-positive, you can also ignore this issue in your code via the ignore-type annotation