$em is of type object<Doctrine\ORM\EntityManagerInterface>, but the property $_em was declared to be of type object<Doctrine\ORM\EntityManager>. Are you sure that you always receive this specific sub-class here, or does it make sense to add an instanceof check?
Our type inference engine has found a suspicous assignment of a value to a property.
This check raises an issue when a value that can be of a given class or a super-class
is assigned to a property that is type hinted more strictly.
Either this assignment is in error or an instanceof check should be added for that assignment.
It seems like the type of the argument is not accepted by the function/method which you are calling.
In some cases, in particular if PHP’s automatic type-juggling kicks in this might be fine. In other cases, however this might be a bug.
We suggest to add an explicit type cast like in the following example: