fix notice in FormProcessor API

CHANGELOG.md

 Version 1.7 (not yet released)
 ===========
-
+* fixed notice in FormProcessor->invokeFormProcessor
 
 
 Version 1.6

Civi/FormProcessor/API/FormProcessor.php

@@ -244,8 +244,9 @@
           }
         }
       }
-
-			$dataBag->setInputData($objInput, $inputType->normalizeValue($params[$objInput->name]));
+      if (isset($params[$objInput->name])) {
+        $dataBag->setInputData($objInput, $inputType->normalizeValue($params[$objInput->name]));
+      }
 		}
 
 		// Execute the actions