Angular2：将<select>组合框绑定到从ngOnInit（）中的API检索到的对象列表时，运行时错误

我正在忙于angular2 Web应用程序，我有一个选择html组合框，我正尝试将其绑定到一系列Active Stock Take对象。我的应用程序似乎可以编译，没有任何问题，但是出现以下运行时错误。知道这意味着什么吗？我会以错误的方式处理吗？使用可以安全导航吗？

我的错误：

zone.js:420
Unhandled Promise rejection:Cannot set property 'stack' of undefined; Zone:<root>; Task:Promise.then; Value:TypeError: Cannot set property 'stack' of undefined
    at SyntaxError.set [as stack] (
http://localhost:4200/vendor.bundle.js:75980:61)
    at assignAll (
http://localhost:4200/vendor.bundle.js:111629:29)
    at SyntaxError.ZoneAwareError (
http://localhost:4200/vendor.bundle.js:111700:16)
    at SyntaxError.BaseError [as constructor] (
http://localhost:4200/vendor.bundle.js:75942:16)
    at new SyntaxError (
http://localhost:4200/vendor.bundle.js:6861:16)
    at TemplateParser.parse (
http://localhost:4200/vendor.bundle.js:21436:19)
    at JitCompiler._compileTemplate (
http://localhost:4200/vendor.bundle.js:55485:68)
    at 
http://localhost:4200/vendor.bundle.js:55368:62

    at Set.forEach (native)
    at JitCompiler._compileComponents (
http://localhost:4200/vendor.bundle.js:55368:19)
    at createResult (
http://localhost:4200/vendor.bundle.js:55251:19)
    at ZoneDelegate.invoke (
http://localhost:4200/vendor.bundle.js:111167:26)
    at Zone.run (
http://localhost:4200/vendor.bundle.js:111038:43)
    at 
http://localhost:4200/vendor.bundle.js:111460:57

    at ZoneDelegate.invokeTask (
http://localhost:4200/vendor.bundle.js:111200:35)
TypeError: Cannot set property 'stack' of undefined
    at SyntaxError.set [as stack] (
http://localhost:4200/vendor.bundle.js:75980:61)
    at assignAll (
http://localhost:4200/vendor.bundle.js:111629:29)
    at SyntaxError.ZoneAwareError (
http://localhost:4200/vendor.bundle.js:111700:16)
    at SyntaxError.BaseError [as constructor] (
http://localhost:4200/vendor.bundle.js:75942:16)
    at new SyntaxError (
http://localhost:4200/vendor.bundle.js:6861:16)
    at TemplateParser.parse (
http://localhost:4200/vendor.bundle.js:21436:19)
    at JitCompiler._compileTemplate (
http://localhost:4200/vendor.bundle.js:55485:68)
    at 
http://localhost:4200/vendor.bundle.js:55368:62

    at Set.forEach (native)
    at JitCompiler._compileComponents (
http://localhost:4200/vendor.bundle.js:55368:19)
    at createResult (
http://localhost:4200/vendor.bundle.js:55251:19)
    at ZoneDelegate.invoke (
http://localhost:4200/vendor.bundle.js:111167:26)
    at Zone.run (
http://localhost:4200/vendor.bundle.js:111038:43)
    at 
http://localhost:4200/vendor.bundle.js:111460:57

    at ZoneDelegate.invokeTask (
http://localhost:4200/vendor.bundle.js:111200:35)
zone.js:422
list of 1 items
aaZoneAwareError{stack: "Error: Uncaught (in promise): TypeError: Cannot se…calhost:4200/vendor.bundle.js:111358:35) [<root>]", message: "Uncaught (in
promise): TypeError: Cannot set prope…http://localhost:4200/vendor.bundle.js:111200:35)", originalStack: "Error: Uncaught (in promise): TypeError: Cannot
se…http://localhost:4200/vendor.bundle.js:111358:35)", zoneAwareStack: "Error: Uncaught (in promise): TypeError: Cannot se…calhost:4200/vendor.bundl

我的html：

<select class="form-control" [(ngModel)]="activeStockTakes?">
    <option *ngFor="let activeStockTake of activeStockTakes" [ngValue]="activeStockTake">{{activeStockTake.UserCode}} - {{activeStockTake.Comment}}
    </option>
</select>

我的stock-takeComponent.ts的ngOninit：

this.restService.getActiveStockTakes()
  .subscribe(
   res => {
    this.activeStockTakes = res;
    console.log(this.activeStockTakes);
   },
   res => {
    console.log(res);
   }
  );
}