Handle error when generating new project in existing directory

[zie1ony]

Scenario

[2022/11/22 13:53:25] ziel ~ 
o_0 > mkdir aaa
[2022/11/22 13:54:25] ziel ~ 
o_0 > cargo odra new --name aaa
⚠️   Favorite `odradev/odra-template` not found in config, using it as a git repository: https://github.com/odradev/odra-template.git
date => '2022-11-22'
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: ⛔   Target directory already exists, aborting!', src/actions/init.rs:59:10
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

The error should be much cleaner.