fix(collapse-demo): add default value for message (#5659)

Author: daniloff200

demo/src/app/components/+collapse/collapse-section.list.ts

@@ -45,10 +45,10 @@ export const demoComponentContent: ContentSection[] = [
         anchor: 'events',
         component: require('!!raw-loader!./demos/events/events'),
         html: require('!!raw-loader!./demos/events/events.html'),
-        description: `Collapse directive exposes 4 events: <code>collapses</code>, that fires when a collapse was triggered (aniamtion start),
-                        <code>collapsed</code>, that fires when a content was hidden (aniamtion finished), 
+        description: `Collapse directive exposes 4 events: <code>collapses</code>, that fires when a collapse was triggered (animation start),
+                        <code>collapsed</code>, that fires when a content was hidden (animation finished),
                         <code>expands</code>, that fires when a expansion was triggered (animation start)
-                      and <code>expanded</code>, that fires when a content was shown\`, and <code>expanded</code>, that fires when a content was shown`,
+                      and <code>expanded</code>, that fires when a content was shown`,
         outlet: CollapseDemoEventsComponent
       },
       {

demo/src/app/components/+collapse/demos/events/events.ts

@@ -6,7 +6,7 @@ import { Component } from '@angular/core';
 })
 export class CollapseDemoEventsComponent {
   isCollapsed = false;
-  message: string;
+  message: string = 'expanded';
 
   collapsed(): void {
     this.message = 'collapsed';