Issue #3432393: Service definition callbacks are not being executed anymore

js/klaro.drupal.js

@@ -13,8 +13,10 @@
                 drupalSettings.klaroConfig.services[index].callback !==
                 undefined
               ) {
-                drupalSettings.klaroConfig.services[index].callback = () =>
-                  drupalSettings.klaroConfig.services[index].callback;
+                drupalSettings.klaroConfig.services[index].callback =
+                  new Function(
+                    `return ${drupalSettings.klaroConfig.services[index].callback}`,
+                  )();
               }
             });
           }