inspector: Avoid a NULL deref
inspector: Avoid a NULL deref

Coverity pointed out that getting a class name requires
dereferencing the pointer, so only don't do it if it is NULL.

Adamovskiy/gtk,Adamovskiy/gtk,davidgumberg/gtk,jigpu/gtk,chergert/gtk,alexlarsson/gtk,chergert/gtk,jigpu/gtk,chergert/gtk,jadahl/gtk,jadahl/gtk,grubersjoe/adwaita,jadahl/gtk,Adamovskiy/gtk,alexlarsson/gtk,davidgumberg/gtk,chergert/gtk,chergert/gtk,davidgumberg/gtk,davidgumberg/gtk,jigpu/gtk,jigpu/gtk,davidgumberg/gtk,Adamovskiy/gtk,jigpu/gtk,grubersjoe/adwaita,grubersjoe/adwaita,alexlarsson/gtk,chergert/gtk,davidgumberg/gtk,alexlarsson/gtk,grubersjoe/adwaita,Adamovskiy/gtk,grubersjoe/adwaita,jadahl/gtk,Adamovskiy/gtk,Adamovskiy/gtk,jigpu/gtk,jadahl/gtk,jadahl/gtk,jigpu/gtk,chergert/gtk,chergert/gtk,alexlarsson/gtk,grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita,jadahl/gtk,alexlarsson/gtk,Adamovskiy/gtk,davidgumberg/gtk,alexlarsson/gtk,alexlarsson/gtk,jadahl/gtk,jigpu/gtk,davidgumberg/gtk