Fixed unknown argument bug

I fixed bug what raised when run known command with unknown argument.

```bash
/ $ ls -alZXV
usage: ls [-h] [-l] [-a]
ls: error: argument -l: ignored explicit argument 'ZXV'

Process finished with exit code 2
```

after patch
```bash
/ $ ls -alZXV
usage: ls [-h] [-l] [-a]
ls: error: argument -l: ignored explicit argument 'ZXCV'
/ $ 
```