Fix ETA loading error

frontend/src/app/components/accelerate-preview/accelerate-preview.component.html

@@ -68,7 +68,7 @@
       <h5 *ngIf="estimate?.pools?.length" i18n="accelerator.how-much-faster">How much faster?</h5>
       <div class="row">
         <div class="col">
-          <ng-container *ngIf="(etaInfo$ | async) as etaInfo">
+          <ng-container *ngIf="(etaInfo$ | async) as etaInfo; else loadingEstimate">
             <small class="form-text text-muted mb-2" i18n="accelerator.hashrate-percentage-description">Your transaction will be prioritized by up to {{ etaInfo.hashratePercentage | number : '1.1-1' }}% of miners.</small>
             <small class="form-text text-muted mb-2" i18n="accelerator.time-estimate-description">This will reduce your expected waiting time until the first confirmation to <app-time kind="within" [time]="etaInfo.acceleratedETA" [fastRender]="false" [fixedRender]="true"></app-time></small>
           </ng-container>

frontend/src/app/components/time/time.component.ts

@@ -78,6 +78,10 @@ export class TimeComponent implements OnInit, OnChanges, OnDestroy {
   }
 
   calculate() {
+    if (!this.time) {
+      return;
+    }
+
     let seconds: number;
     switch (this.kind) {
       case 'since':

frontend/src/app/services/eta.service.ts

@@ -26,7 +26,7 @@ export class EtaService {
 
   getProjectedEtaObservable(estimate: AccelerationEstimate, miningStats?: MiningStats): Observable<{ hashratePercentage: number, ETA: number, acceleratedETA: number }> {
     return combineLatest([
-      this.stateService.mempoolTxPosition$.pipe(map(p => p.position)),
+      this.stateService.mempoolTxPosition$.pipe(map(p => p?.position)),
       this.stateService.difficultyAdjustment$,
       miningStats ? of(miningStats) : this.miningService.getMiningStats('1w'),
     ]).pipe(