Added to unpacker class error warning informaton about file name which could be not opened, then user can check if name was correct etc.
Added to unpacker class error warning informaton about file name which could be not opened, then user can check if name was correct etc.

wkrzemien/j-pet-framework,wkrzemien/j-pet-framework,wkrzemien/j-pet-framework,wkrzemien/j-pet-framework,wkrzemien/j-pet-framework