UTXO spent tracking refactor

refs #1301

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

@@ -81,7 +81,7 @@ export class StateService {
   mempoolInfo$ = new ReplaySubject<MempoolInfo>(1);
   mempoolBlocks$ = new ReplaySubject<MempoolBlock[]>(1);
   txReplaced$ = new Subject<Transaction>();
-  utxoSpent$ = new Subject<null>();
+  utxoSpent$ = new Subject<object>();
   mempoolTransactions$ = new Subject<Transaction>();
   blockTransactions$ = new Subject<Transaction>();
   isLoadingWebSocket$ = new ReplaySubject<boolean>(1);

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

@@ -252,7 +252,7 @@ export class WebsocketService {
     }
 
     if (response.utxoSpent) {
-      this.stateService.utxoSpent$.next();
+      this.stateService.utxoSpent$.next(response.utxoSpent);
     }
 
     if (response.backendInfo) {