Fix regression: error in Form Builder when opening control details
Fix regression: error in Form Builder when opening control details

Regressed with 4939fa4946ab91a19790c56052401e32dc30ce76 #1094.

brunobuzzi/orbeon-forms,ajw625/orbeon-forms,tanbo800/orbeon-forms,wesley1001/orbeon-forms,joansmith/orbeon-forms,martinluther/orbeon-forms,wesley1001/orbeon-forms,joansmith/orbeon-forms,orbeon/orbeon-forms,evlist/orbeon-forms,martinluther/orbeon-forms,orbeon/orbeon-forms,brunobuzzi/orbeon-forms,ajw625/orbeon-forms,orbeon/orbeon-forms,wesley1001/orbeon-forms,martinluther/orbeon-forms,brunobuzzi/orbeon-forms,ajw625/orbeon-forms,evlist/orbeon-forms,brunobuzzi/orbeon-forms,orbeon/orbeon-forms,evlist/orbeon-forms,tanbo800/orbeon-forms,wesley1001/orbeon-forms,evlist/orbeon-forms,tanbo800/orbeon-forms,evlist/orbeon-forms,martinluther/orbeon-forms,ajw625/orbeon-forms,joansmith/orbeon-forms,tanbo800/orbeon-forms,joansmith/orbeon-forms