Fix not loading when preview is not defined
Fix not loading when preview is not defined

Benvii/pannellum,psteph801/psteph801.github.io,riuson/pannellum,quentinyang/pannellum,Benvii/pannellum,Benvii/pannellum,psteph801/psteph801.github.io,mpetroff/pannellum,ywjrg/pannellum,psteph801/psteph801.github.io,ywjrg/pannellum,mpetroff/pannellum,Benvii/pannellum,eric-seekas/pannellum,eric-seekas/pannellum,mpetroff/pannellum,riuson/pannellum,ywjrg/pannellum,quentinyang/pannellum,eric-seekas/pannellum,mpetroff/pannellum,ywjrg/pannellum,psteph801/psteph801.github.io,quentinyang/pannellum,riuson/pannellum,quentinyang/pannellum,eric-seekas/pannellum,riuson/pannellum