i18n for internal error

config/locales/js-en.yml

@@ -63,6 +63,8 @@ en:
     description_select_work_package: "Select work package #%{id}"
     description_selected_columns: "Selected Columns"
     description_subwork_package: "Child of work package #%{id}"
+    error:
+      internal: "An internal error has occcurred."
     filter:
       description:
         text_open_filter: "Open this filter with 'ALT' and arrow keys."

frontend/app/components/wp-edit/wp-notification.service.ts

@@ -53,7 +53,7 @@ export class WorkPackageNotificationService {
   }
 
   public showGeneralError() {
-    this.NotificationsService.addError("An internal error has occcurred.");
+    this.NotificationsService.addError(I18n.t('js.error.internal'));
   }
 
   private showCustomError(errorResource, workPackage) {