Handle file package not being available
(elixir) lib/system.ex:791: System.cmd("file", ["--mime-type", "/tmp/plug-1572/multipart-1572379399-933611615736803-2"], [])
(file_info) lib/file_info.ex:16: FileInfo.get_info/1
(ex_optimizer) lib/ex_optimizer.ex:85: ExOptimizer.load_image/1