The issue could also be caused by a filter entry in the build configuration.
If the path has been excluded in your configuration, e.g. excluded_paths:["lib/*"],
you can move it to the dependency path list as follows:
It seems like $area->Elements() can also be of type DNADesign\Elemental\Models\BaseElement; however, parameter $dataList of SilverStripe\Forms\GridF...ridField::__construct() does only seem to accept SilverStripe\ORM\SS_List|null, 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