Made the requirement of a non-nil formatName more explicit.
Made the requirement of a non-nil formatName more explicit.

znatz/FastImageCache,erysaj/FastImageCache,gaurav1981/FastImageCache,lydonchandra/FastImageCache,path/FastImageCache,hunhu/FastImageCache,nKey/FastImageCache,goodheart/FastImageCache,jaredsinclair/FastImageCache,hyperspacemark/FastImageCache,yimouleng/FastImageCache,xb123456456/FastImageCache,dcaunt/FastImageCache,wangmb/FastImageCache,indraj/FastImageCache,rock88/FastImageCache,zjh171/FastImageCache,DeskConnect/FastImageCache,zilaiyedaren/FastImageCache,georgekola/FastImageCache,globchastyy/FastImageCache,irealme/FastImageCache,King-of-Monkey/FastImageCache,ramoslin02/FastImageCache,libiao88/FastImageCache