The type HasRelationsRecordsTrait for parameter $manager is a trait, and thus cannot be used for type-hinting in PHP. Maybe consider adding an interface and use that for type-hinting?
It seems like $manager of type object<Nip\Records\Trait...sRelationsRecordsTrait> is incompatible with the declared type object<Nip\Records\AbstractModels\RecordManager> of property $manager.
Our type inference engine has found an assignment to a property that is incompatible
with the declared type of that property.
Either this assignment is in error or the assigned type should be added
to the documentation/type hint for that property..