Support fallback app icons

dashboard/src/components/AppsView.vue

@@ -19,7 +19,7 @@
       <TransitionGroup name="grid-animation" tag="div" class="grid" v-if="viewType === VIEW_TYPE.GRID">
         <a v-for="app in filteredApps" :key="app.id" class="grid-item" @click="onOpenApp(app, $event)" :href="'https://' + app.fqdn" target="_blank" v-tooltip="app.fqdn">
           <div class="config" v-show="isOperator(app)" @click.prevent="openAppEdit(app)"><Icon icon="fa-solid fa-cog" /></div>
-          <img :src="API_ORIGIN + app.iconUrl"/>
+          <img :src="API_ORIGIN + app.iconUrl" v-fallback-image="API_ORIGIN + '/img/appicon_fallback.png'"/>
           <div class="grid-item-label">{{ app.label || app.subdomain || app.fqdn }}</div>
           <div class="grid-item-task-label">{{ installationStateLabel(app) }}</div>
           <div class="apps-progress" v-show="isOperator(app)">
@@ -32,7 +32,7 @@
         <TableView :columns="listColumns" :model="filteredApps">
           <template #icon="slotProps">
             <a :href="'https://' + slotProps.fqdn" target="_blank">
-              <img class="list-icon" :src="API_ORIGIN + slotProps.iconUrl"/>
+              <img class="list-icon" :src="API_ORIGIN + slotProps.iconUrl" v-fallback-image="API_ORIGIN + '/img/appicon_fallback.png'"/>
             </a>
           </template>
           <template #label="slotProps">