Fix viewer locking up on scene change when fade is specified but renderer doesn't return image data (fixes #430).
Fix viewer locking up on scene change when fade is specified but renderer doesn't return image data (fixes #430).

psteph801/psteph801.github.io,mpetroff/pannellum,psteph801/psteph801.github.io,psteph801/psteph801.github.io,mpetroff/pannellum,mpetroff/pannellum,mpetroff/pannellum,psteph801/psteph801.github.io