workspacescene: Fix a potential crash in isCandidate.
This fixes a crash on my computer with AMD GPU, when logging in from SDDM or PLM. The DRM format being queried was "RG16", which is not in the format list.
This fixes a crash on my computer with AMD GPU, when logging in from SDDM or PLM. The DRM format being queried was "RG16", which is not in the format list.