Fix js crash in node page and add loading spinner to channel tree chart

frontend/src/app/lightning/channels-list/channels-list.component.html

@@ -87,8 +87,6 @@
 </ng-template>
 
 <ng-template #skeleton>
-  <h2 class="float-left" i18n="lightning.channels">Channels</h2>
-
   <table class="table table-borderless">
   <ng-container *ngTemplateOutlet="tableHeader"></ng-container>
   <tbody>