adapt yes-no component to reflect changes better

src/app/shared/components/yes-no/yes-no.component.html

 <div class="content">
   <app-tag-item
-    [iconName]="selected ? 'check' : null"
+    [iconName]="selected === true ? 'check' : null"
     [label]="'Oui'"
-    [color]="selected ? 'black' : 'white'"
+    [color]="selected === true ? 'black' : 'white'"
     [clickable]="true"
-    (action)="selected = true; clicked()"
+    (action)="clicked(true)"
   />
   <app-tag-item
-    [iconName]="selected !== null && !selected ? 'check' : null"
+    [iconName]="selected === false ? 'check' : null"
     [label]="'Non'"
-    [color]="selected !== null && !selected ? 'black' : 'white'"
+    [color]="selected === false ? 'black' : 'white'"
     [clickable]="true"
-    (action)="selected = false; clicked()"
+    (action)="clicked(false)"
   />
 </div>

src/app/shared/components/yes-no/yes-no.component.ts

@@ -7,11 +7,10 @@ import { Component, EventEmitter, Input, Output } from '@angular/core';
 })
 export class YesNoComponent {
   /** Selected or not */
-  @Input({ required: true }) selected: boolean = null;
-
+  @Input() selected: boolean | null = null;
   @Output() selectedEvent = new EventEmitter<boolean>();
 
-  public clicked(): void {
-    this.selectedEvent.emit(this.selected);
+  public clicked(value: boolean): void {
+    this.selectedEvent.emit(value);
   }
 }