Plugin could not be deleted due to an error: Could not fully remove the plugin(s) my-plugin/my-plugin.php

[admin]

Why uninstalling the following (empty) plugin results in error?

Here is

my-plugin/my-plugin.php

:

<?php
/*
Plugin Name: My Plugin
*/

and

my-plugin/uninstall.php

:

<?php

When I click 'Delete' and then confirm, I get the following error:

<blockquote>
Plugin could not be deleted due to an error: Could not fully remove
the plugin(s) my-plugin/my-plugin.php.
</blockquote>

What's wrong here?

<hr>

~/Sites/wordpress/wp-content/plugins/my-plugin $ ls -ll
total 16
-rwxrwxrwx@ 1 me  staff  34 13 Aug 21:43 my-plugin.php
-rwxrwxrwx@ 1 me  staff   6 13 Aug 21:44 uninstall.php