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).

首先跟踪验证路径，以及如何确定 --validate、--ext 和 --attr 的位置参数。复现报告中的命令，然后调整处理方式，使有效的标志值不会产生“Not found”消息，同时验证和标志解析继续正常工作。

由索引模型根据 Issue 内容生成。