I have found that Archiver.UnZip will crash if the zip file is empty
Because of this I went to check the file for empty doing a Archive.NumberOfZipEntries <> 0 and that also crashes
So to protect myself from crashing I now get the File.Size and it it's less then a 100 bytes I assume it is empty and don't try to do anything with it.
100 bytes is just a number I picked knowing that I will never have a zip file less then this.
Attached is the file I was checking. Found it crashed on Android 5.1
Just a heads up.