Plugins can't be activated with a language file with an empty array

[PerJensen]

This is the return array and the error:

return array(   
    //'example' => 'Example',
);

customizations (guid: 20) cannot start and has been deactivated.
Reason: Cannot register languages for plugin customizations (guid: 20) at ...

[juho-jaakkola]

Indeed.

• Array is checked here: https://github.com/Elgg/Elgg/blob/1.9/engine/lib/languages.php#L93
• Exception is thrown here https://github.com/Elgg/Elgg/blob/1.9/engine/lib/languages.php#L239
• ...and catched here: https://github.com/Elgg/Elgg/blob/1.9/engine/lib/plugins.php#L349

I'm not sure if this should be considered a bug or not. It is maybe a bit overkill to disable the whole plugin.

This problem will most likely be fixed once the overhaul for the i18n code gets finished. Let's keep this open until that.

[PerJensen]

Lets do that. Maybe it's not a bug, but I see no reason not to allow the plugin to activate.

[jdalsem]

Provided a PR to fix this, as it plugins are shown as activatable, but crash during activating as the language file was empty. The PR correctly handles the situation where there is a language file, but it returns an empty array

[PerJensen]

Nice fix and working, tested manually.