diff --git a/web/static/src/ts/core/Widget.ts b/web/static/src/ts/core/Widget.ts
index 7aa71c99..84848038 100644
--- a/web/static/src/ts/core/Widget.ts
+++ b/web/static/src/ts/core/Widget.ts
@@ -46,7 +46,7 @@ export class Widget<T extends WEnv, Props> {
 
   env: T;
   state: Object = {};
-  props: Props | undefined;
+  props: Props;
   refs: { [key: string]: Widget<T, {}> | HTMLElement | undefined } = {};
 
   //--------------------------------------------------------------------------
@@ -55,7 +55,12 @@ export class Widget<T extends WEnv, Props> {
 
   constructor(parent: Widget<T, {}> | T, props?: Props) {
     wl.push(this);
-    this.props = props;
+
+    // is this a good idea?
+    //   Pro: if props is empty, we can create easily a widget
+    //   Con: this is not really safe
+    //   Pro: but creating widget (by a template) is always unsafe anyway
+    this.props = <Props>props;
     let id: number;
     let p: Widget<T, any> | null = null;
     if (parent instanceof Widget) {
diff --git a/web/static/src/ts/widgets/notification.ts b/web/static/src/ts/widgets/notification.ts
index b3a8e15f..81c4d456 100644
--- a/web/static/src/ts/widgets/notification.ts
+++ b/web/static/src/ts/widgets/notification.ts
@@ -19,6 +19,6 @@ export class Notification extends Widget<Env, INotification> {
   template = template;
 
   close() {
-    this.env.notifications.close(this.props!.id);
+    this.env.notifications.close(this.props.id);
   }
 }