Check if FieldList has tabset before trying to add cms fields to tabs.

[3Dgoo]

If we try to add Translatable to the File class the files section errors.

This is because Folder is a type of File. In Translatable.php we have the following code:

$tab = $fields->findOrMakeTab('Root.Translations', _t('Translatable.TRANSLATIONS', 'Translations'));

The problem is Folder does not have a Root tab, so this line errors.

I have wrapped this section of code with a check to see if $fields has a tabset defined before trying to add tabs.

[dhensby]

seems legit to me, would you mind squashing the 2 commits, please?

[3Dgoo]

I have squashed the 2 commits together as requested.

[dhensby]

thanks!