Validation prints `Not found [target]` message for every flag

Version used is 0.9.91.

Running validation with any flags prints a message to console due to how the `positional` args are determined.

E.g. running `--validate src/ --ext foo --attr bar` results in:

```
Not found: /foo
Not found: /bar
```

This is more of a cosmetic issue. I was confused at first when I saw the messages and unsure if my flags were even correctly parsed or not (turns out they are).