Lightning indexing indicators

refs  #2647

frontend/src/app/lightning/nodes-channels-map/nodes-channels-map.component.html

@@ -18,5 +18,8 @@
     <div class="text-center loading-spinner" [class]="style" *ngIf="isLoading && !disableSpinner">
       <div class="spinner-border text-light"></div>
     </div>
+    <div *ngIf="showIndexingInProgress" class="indexing-message">
+      <span class="badge badge-pill badge-warning" i18n="lightning.indexing-in-progress">Indexing in progress</span>
+    </div>
   </ng-container>
 </div>

frontend/src/app/lightning/nodes-channels-map/nodes-channels-map.component.scss

@@ -133,3 +133,10 @@
     top: 450px;
   }
 }
+
+.indexing-message {
+  position: absolute;
+  width: 100%;
+  text-align: center;
+  margin-top: 100px;
+}

frontend/src/app/lightning/nodes-channels-map/nodes-channels-map.component.ts

@@ -36,6 +36,7 @@ export class NodesChannelsMap implements OnInit {
   channelCurve = 0;
   nodeSize = 4;
   isLoading = false;
+  showIndexingInProgress = false;
 
   chartInstance = undefined;
   chartOptions: EChartsOption = {};
@@ -206,6 +207,8 @@ export class NodesChannelsMap implements OnInit {
     let title: object;
     if (channels.length === 0 && !this.placeholder) {
       this.chartOptions = null;
+      this.showIndexingInProgress = true;
+      this.isLoading = false;
       return;
     }