CC Lite throws errors when changing options

As long as I didn't change any parameters, CC Lite would work as expected and let me assign licences to nodes and show them.

But as soon as I changed a parameter like "Default license", "Allowed licenses" or "License jurisdiction" under "admin/settings/creativecommons-lite" any content type with an assigned CC-Lite option would throw this error upon pushing the "Edit" button of a node instead of letting me edit the node:
Fatal error: Call to undefined function: array_intersect_key() in (...host path removed ...)/sites/all/modules/creativecommons_lite/creativecommons_lite.module on line 311,
which, IMHO refers to the line:

$types = array_intersect_key($types, $options);
  }

For now only deactivating the module has made nodes accessible again and I have found no workaround so far.