Is the alpha release usable/testable?

I am an Emacs beginner, I try to use phpactor.el to improve my PHP experience.
I installed phpactor by following the [standalone][1] way and it seems to be working. When I use it in my directory it works.
I've installed phpactor.el by using `package-install` in Emacs.
When I use Emacs to type code, automatically in the mini buffer I see an error.

Here is a code to reproduce it. My point is after the arrow (where I put a pipe) when I the an error.

```php
|
```

The error I get:

`Phpactor: Unknown item "", known items: "", "", ""`

Testing the Phpactor installation:

```bash
$ phpactor status
Version: 7db7a5c (il y a 4 semaines) updated-composer-749
Filesystems: git, simple, composer
Working directory: /var/www/html/work/libs/myrepo

Config files (missing is not bad):

✘ /home/john/.config/phpactor/phpactor.json
✘ /home/john/.config/phpactor/phpactor.yml
✘ /var/www/html/work/libs/myrepo/.phpactor.json
✘ /var/www/html/work/libs/myrepo/.phpactor.yml

Diagnostics:

✔ Composer detected - faster class location and more features!
✔ Git detected - enables faster refactorings in your repository scope!
✔ XDebug is disabled. XDebug has a negative effect on performance.
```

My `.emacs` about phpactor.el.

```lisp
(add-hook 'php-mode-hook
(lambda ()
(make-local-variable 'eldoc-documentation-function)
(setq eldoc-documentation-function
'phpactor-hover)))
```

Since phpactor is under development and phpactor.el is in _alpha_ version, is it usable/testable? Is the error from me/my install, or the plugin isn't usable?
As a side note I'll add that I'm already using phpactor in Vim (in Vim it's not using the standalone install I think though).

[1]: https://phpactor.github.io/phpactor/standalone.html