Fixes: U4-2690 data type editor, makes 2 requests for the initial load

src/Umbraco.Web.UI.Client/src/views/datatype/datatype.edit.controller.js

@@ -70,8 +70,9 @@ function DataTypeEditController($scope, $routeParams, $location, dataTypeResourc
     }
     
     $scope.$watch("content.selectedEditor", function (newVal, oldVal) {
+
         //when the value changes, we need to dynamically load in the new editor
-        if (newVal !== null && newVal !== undefined && newVal != oldVal) {
+        if (oldVal !== null && newVal !== null && newVal !== undefined && newVal != oldVal) {
             //we are editing so get the content item from the server
             var currDataTypeId = $routeParams.create ? undefined : $routeParams.id;
             dataTypeResource.getPreValues(newVal, currDataTypeId)