Not every tile server provides tiles for every zoom level from 0 to 19. Sometimes the server may respond with empty file which will be cached (good), send to the requester (good) and processed by if (bad). Check size of the image prior to processing and if it's zero length just ignore. Otherwise the app crashes.
Not every tile server provides tiles for every zoom level from 0 to 19. Sometimes the server may respond with empty file which will be cached (good), send to the requester (good) and processed by if (bad). Check size of the image prior to processing and if it's zero length just ignore. Otherwise the app crashes.