tidy up acceleration dashboard

frontend/src/app/components/acceleration-stats/acceleration-stats.component.ts

@@ -2,7 +2,6 @@ import { ChangeDetectionStrategy, Component, Input, OnInit } from '@angular/core
 import { Observable, of } from 'rxjs';
 import { switchMap } from 'rxjs/operators';
 import { ApiService } from '../../services/api.service';
-import { StateService } from '../../services/state.service';
 
 @Component({
   selector: 'app-acceleration-stats',
@@ -13,9 +12,10 @@ import { StateService } from '../../services/state.service';
 export class AccelerationStatsComponent implements OnInit {
   @Input() timespan: '24h' | '1w' = '24h';
   public accelerationStats$: Observable<any>;
-  private lastBlockHeight: number;
 
-  constructor(private apiService: ApiService, private stateService: StateService) { }
+  constructor(
+    private apiService: ApiService,
+  ) { }
 
   ngOnInit(): void {
     this.accelerationStats$ = this.apiService.getAccelerations$(this.timespan).pipe(