local-repo error message can be confusing

### I confirm that...

- [X] I have searched the [issue tracker](https://github.com/doomemacs/doomemacs/issues), [documentation](https://docs.doomemacs.org), [FAQ](https://docs.doomemacs.org/-/faq), [Discourse](https://discourse.doomemacs.org), and [Google](https://google.com), in case this issue has already been reported/resolved.

- [X] I have read "[How to Debug Issues](https://doomemacs.org/d/how2debug)", and will use it to provide as much information about this issue as possible.

- [X] The issue can be reproduced on the **latest** available commit of Doom.

- [X] The issue can be reproduced on a stable release of Emacs, such as 27 or 28. *(Doom does not support development builds like 29+ or any version ending in .50 or .9x)*

### Expected behavior

```
(package! test
:recipe (:local-repo "/test"))
```
should say /test doesn't exist.

### Current behavior

```
Message: No ':repo' specified for package 'test'
```

### Steps to reproduce

Put in packages.el
```
(package! test
:recipe (:local-repo "/test"))
```

```
doom sync
```

### System Information

https://pastebin.com/wFhyP5vZ