Fix potentially null reference if drawable was not assigned a `LoadThread` yet
Fix potentially null reference if drawable was not assigned a `LoadThread` yet

peppy/osu-framework,ppy/osu-framework,peppy/osu-framework,smoogipooo/osu-framework,ppy/osu-framework,ppy/osu-framework,smoogipooo/osu-framework,peppy/osu-framework