Do not compute cache key in case of nil image
Do not compute cache key in case of nil image

luisrecuenco/LRImageManager,vhoto-dev/LRImageManager,luisrecuenco/LRImageManager,toto/LRImageManager,Wallapop/LRImageManager,toto/LRImageManager,vhoto-dev/LRImageManager,toto/LRImageManager,vhoto-dev/LRImageManager,luisrecuenco/LRImageManager