Argument must be an instance of Mage_Core_Model_Config_Element, array given

Recoverable Error: Argument 1 passed to Df_Adminhtml_Model_Translator_Config::getHelperModuleMf() must be an instance of Mage_Core_Model_Config_Element, array given, called in /..../httpdocs/app/code/local/Df/Adminhtml/Model/Config.php on line 32 and defined  in /..../httpdocs/app/code/local/Df/Adminhtml/Model/Translator/Config.php on line 7

#0 /..../httpdocs/app/code/local/Df/Adminhtml/Model/Translator/Config.php(7): mageCoreErrorHandler(4096, 'Argument 1 pass...', '/var/www/vhosts...', 7, Array)
#1 /..../httpdocs/app/code/local/Df/Adminhtml/Model/Config.php(32): Df_Adminhtml_Model_Translator_Config->getHelperModuleMf(Array)
#2 /..../httpdocs/app/code/core/Mage/Adminhtml/Model/Config.php(222): Df_Adminhtml_Model_Config->getAttributeModule(Array, NULL, NULL)
#3 /..../httpdocs/app/code/core/Mage/Adminhtml/Block/System/Email/Template/Edit.php(386): Mage_Adminhtml_Model_Config->getSystemConfigNodeLabel('customer')
#4 /..../httpdocs/app/code/core/Mage/Adminhtml/Block/System/Email/Template/Edit.php(333): Mage_Adminhtml_Block_System_Email_Template_Edit->_getSystemConfigPathsParts(Array)
#5 /..../httpdocs/app/design/adminhtml/default/default/template/system/email/template/edit.phtml(132): Mage_Adminhtml_Block_System_Email_Template_Edit->getUsedCurrentlyForPaths()
#6 /..../httpdocs/app/code/core/Mage/Core/Block/Template.php(241): include('/var/www/vhosts...')
#7 /..../httpdocs/app/code/core/Mage/Core/Block/Template.php(272): Mage_Core_Block_Template->fetchView('adminhtml/defau...')
#8 /..../httpdocs/app/code/core/Mage/Core/Block/Template.php(286): Mage_Core_Block_Template->renderView()
#9 /..../httpdocs/app/code/core/Mage/Adminhtml/Block/Template.php(81): Mage_Core_Block_Template->_toHtml()
#10 /..../httpdocs/app/code/core/Mage/Core/Block/Abstract.php(919): Mage_Adminhtml_Block_Template->_toHtml()
#11 /..../httpdocs/app/code/local/Df/Core/Block/Text/List.php(20): Mage_Core_Block_Abstract->toHtml()
#12 /..../httpdocs/app/code/core/Mage/Core/Block/Abstract.php(919): Df_Core_Block_Text_List->_toHtml()
#13 /..../httpdocs/app/code/core/Mage/Core/Block/Abstract.php(637): Mage_Core_Block_Abstract->toHtml()
#14 /..../httpdocs/app/code/core/Mage/Core/Block/Abstract.php(581): Mage_Core_Block_Abstract->_getChildHtml('content', true)
#15 /..../httpdocs/app/design/adminhtml/default/default/template/page.phtml(74): Mage_Core_Block_Abstract->getChildHtml('content')
#16 /..../httpdocs/app/code/core/Mage/Core/Block/Template.php(241): include('/var/www/vhosts...')
#17 /..../httpdocs/app/code/core/Mage/Core/Block/Template.php(272): Mage_Core_Block_Template->fetchView('adminhtml/defau...')
#18 /..../httpdocs/app/code/core/Mage/Core/Block/Template.php(286): Mage_Core_Block_Template->renderView()
#19 /..../httpdocs/app/code/core/Mage/Adminhtml/Block/Template.php(81): Mage_Core_Block_Template->_toHtml()
#20 /..../httpdocs/app/code/core/Mage/Core/Block/Abstract.php(919): Mage_Adminhtml_Block_Template->_toHtml()
#21 /..../httpdocs/app/code/core/Mage/Core/Model/Layout.php(555): Mage_Core_Block_Abstract->toHtml()
#22 /..../httpdocs/app/code/core/Mage/Core/Controller/Varien/Action.php(390): Mage_Core_Model_Layout->getOutput()
#23 /..../httpdocs/app/code/core/Mage/Adminhtml/controllers/System/Email/TemplateController.php(109): Mage_Core_Controller_Varien_Action->renderLayout()
#24 /..../httpdocs/app/code/core/Mage/Core/Controller/Varien/Action.php(418): Mage_Adminhtml_System_Email_TemplateController->editAction()
#25 /..../httpdocs/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(250): Mage_Core_Controller_Varien_Action->dispatch('edit')
#26 /..../httpdocs/app/code/core/Mage/Core/Controller/Varien/Front.php(172): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))
#27 /..../httpdocs/app/code/core/Mage/Core/Model/App.php(354): Mage_Core_Controller_Varien_Front->dispatch()
#28 /..../httpdocs/app/Mage.php(684): Mage_Core_Model_App->run(Array)
#29 /..../httpdocs/index.php(103): Mage::run('', 'store')
#30 {main}