Compression flag --output not working with single file compression.

[marcospb19]

Originally posted by @vrmiguel in #89 (comment)

Problem

The flag --output is not working properly when compressing one file into one non-archive format compressed file.

# Works
$ cargo run -- c src/main.rs main.rs.xz 

# Panics
$ cargo run -- d main.rs.xz -o some-new-folder
thread 'main' panicked at 'No such file or directory (os error 2)', src/error.rs:173:45
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

[marcospb19]

Waiting on issue #56 to be solved first, as it will help us debug what's the cause.

[marcospb19]

Not waiting anymore, Figdosa just knew where the problem was 😎.