[Neos] NeosDemo Localisation: remove en_US dependency

[armin otto]

I want to modify the NEOS demo site to support language and country localisation.
Meaning, that I want to e.g. have two english and two german versions of the same site, where only sites with the same language inherit from each other.

To achive this I edited the Settings.yaml like this:

 TYPO3CR:
    contentDimensions:
      'language':
        default: 'en_US'
        defaultPreset: 'en_US'
        presets:
          'all': ~
          'en_US':
            label: 'USA'
            values: ['en_US']
            uriSegment: 'en'
          'en_UK':
            label: 'UK'
            values: ['en_UK', 'en_US']
            uriSegment: 'uk'
          'de':
            label: 'Germany'
            values: ['de']
            uriSegment: 'de'
          'at':
            label: 'Austria'
            values: ['at','de']
            uriSegment: 'at'

After cleaning up the old nodes, this works fine with one exception: The footer.
This is the error message I get:

Exception while rendering
page<TYPO3.Neos:Page>/
body<TYPO3.TypoScript:Template>/
footer/
__meta/
override/
contentCollectionNode:
No content collection of type TYPO3.Neos:ContentCollection could be found in the current node and no node path was provided. You might want to configure the nodePath property with a relative path to the content collection. (201504300607472797b8)

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This error occurs on all languages where I remove the 'en_US' value.
Is there a way to make make a language independent from the USA?