It seems like $this->getConfigProvider() can also be of type null; however, parameter $configProvider of SlayerBirden\DFCodeGener...nd::setConfigProvider() does only seem to accept SlayerBirden\DFCodeGener...ConfigProviderInterface, 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