The trait Illuminate\Queue\SerializesModels requires some properties which are not provided by mathewparet\LaravelInvites\Mail\InvitationMail: $id, $class, $relations
It seems like __(config('laravelinvite...> config('app.name')))) can also be of type array; however, parameter $subject of Illuminate\Mail\Mailable::subject() does only seem to accept string, maybe add an additional type check?
(
Ignorable by Annotation
)
If this is a false-positive, you can also ignore this issue in your code via the ignore-type annotation