Merge pull request #1919 from emanuelschuetze/fix1904

Fixed TypeError caused by #1904.

openslides/core/static/js/core/base.js

@@ -149,6 +149,7 @@ angular.module('OpenSlidesApp.core', [
     function (DS) {
         return function (collection, instance) {
             var Resource = DS.definitions[collection];
+            if (Resource.relationList) {
                 Resource.relationList.forEach(function (relationDef) {
                     if (relationDef.foreignKey) {
                         var query = {};
@@ -158,6 +159,7 @@ angular.module('OpenSlidesApp.core', [
                 });
             }
         }
+    }
 ])
 
 .run([