title: async await in switch case statement does not work
body: <p>can we wait for the resolution of a promise within switch case statement, using the keyword await? in my angular component I have the following code which crashes my application.</p>
  
  <pre><code>switch (this.status) {
                  case 'opened':
                    break;
                  case 'payed':
                    this.getIntervalStatusSubscription.unsubscribe();
                    this.localStorageService.storePaymentIsMade(true);
                    await this.dbService.addOrderPaymentResult(ProcessResult.done, this.printerVMService.getSessionId()).toPromise();
                    this.router.navigate(['welcome/paying/paying_accepted']);
                    break;
                  case 'closed':
                    this.getIntervalStatusSubscription.unsubscribe();
                    this.paymentSessionIsClosed = true;
                   await this.dbService.addOrderPaymentResult(ProcessResult.error, this.printerVMService.getSessionId()).toPromise();
                    this.router.navigate(['welcome']);
                    break;
                  case 'used':
                    this.getIntervalStatusSubscription.unsubscribe();
                    this.router.navigate(['welcome']);
                    break;
                  default:
                    console.error('status don\'t exist');
                    this.utils.displayAlertError(this.device.getIntervalStatus);
                    this.router.navigate(['welcome']);
                }
  </code></pre>
  
  <p>After several tests, the error seems to me to come from lines starting with <code>await</code>.
  Can you tell me what's wrong please. I would like <code>this.dbService.addOrderPaymentResult(ProcessResult.done, this.printerVMService.getSessionId())</code> which returns an observable is executed synchronously before going to
  <code>this.router.navigate(['welcome/paying/paying_accepted']);</code> that's why i chose to use <code>toPromise()</code> and <code>await</code></p>