C# ViewDidLoad上的MVVM交叉崩溃

在ViewDidLoad上，我的MVVM跨Xamarin应用程序崩溃，错误如下。 针对IOS手机和平板电脑（iPad）的Xamarin IOS应用程序

位于MvvmCross.Core.ViewModels.MvxViewModelLoader.LoadViewModel（MvvmCross.Core.ViewModels.MvxViewModelRequest，IMvxBundle savedState）[0x00000]中：0
在V:\Xamarin\MvvmCross\MvvmCross\MvvmCross\iOS\iOS\Views\MvxViewControllerExtensionMethods.LoadViewModel（IMvxIosView iosView）[0x00059]中的MvvmCross.iOS\Views\MvxViewControllerExtensionMethods.cs:45
在MvvmCross.Core.Views.MvxViewExtensionMethods.OnViewCreate（IMvxView视图，System.Func`1 viewModelLoader）[0x00012]中：0
在V:\Xamarin\MvvmCross\MvvmCross\MvvmCross\iOS\iOS\Views\MvxViewControllerExtensionMethods.OnViewCreate（IMvxIosView iosView）[0x00001]中的MvvmCross.iOS\Views\MvxViewControllerExtensionMethods.cs:21
在V:\Xamarin\MvvmCross\MvvmCross\MvvmCross\iOS\Views\MvxViewControllerAdapter.handleviewidloadcalled（System.Object sender，System.EventArgs e）[0x00001]中的V:\Xamarin\MvvmCross\MvvmCross\iOS\Views\MvxViewControllerAdapter.cs:28
at（包装器委托调用）：调用\u void\u object\u EventArgs（对象，System.EventArgs）
在V:\Xamarin\MvvmCross\MvvmCross\MvvmCross\Platform\Platform\Core\MvxDelegateExtensionMethods.Raise（System.EventHandler，System.Object sender）[0x00000]中的MvvmCross.Platform\Core\MvxDelegateExtensionMethods.cs:16
在V:\Xamarin\MvvmCross\MvvmCross\MvvmCross\Platform\iOS.Views.MvxEventSourceViewController.viewdiload（）[0x00006]中的MvvmCross.Platform.iOS\Views\MvxEventSourceViewController.cs:63

这是一个不错的调用堆栈。太糟糕了，它没有包含异常类型和异常消息。根据堆栈跟踪，LoadViewModel中存在空指针异常。@Lennie:您是如何解决这个问题的？

at MvvmCross.Core.ViewModels.MvxViewModelLoader.LoadViewModel (MvvmCross.Core.ViewModels.MvxViewModelRequest request, IMvxBundle savedState) [0x00000] in <filename unknown>:0 
  at MvvmCross.iOS.Views.MvxViewControllerExtensionMethods.LoadViewModel (IMvxIosView iosView) [0x00059] in V:\Xamarin\MvvmCross\MvvmCross\iOS\iOS\Views\MvxViewControllerExtensionMethods.cs:45 
  at MvvmCross.Core.Views.MvxViewExtensionMethods.OnViewCreate (IMvxView view, System.Func`1 viewModelLoader) [0x00012] in <filename unknown>:0 
  at MvvmCross.iOS.Views.MvxViewControllerExtensionMethods.OnViewCreate (IMvxIosView iosView) [0x00001] in V:\Xamarin\MvvmCross\MvvmCross\iOS\iOS\Views\MvxViewControllerExtensionMethods.cs:21 
  at MvvmCross.iOS.Views.MvxViewControllerAdapter.HandleViewDidLoadCalled (System.Object sender, System.EventArgs e) [0x00001] in V:\Xamarin\MvvmCross\MvvmCross\iOS\iOS\Views\MvxViewControllerAdapter.cs:28 
  at (wrapper delegate-invoke) <Module>:invoke_void_object_EventArgs (object,System.EventArgs)
  at MvvmCross.Platform.Core.MvxDelegateExtensionMethods.Raise (System.EventHandler eventHandler, System.Object sender) [0x00000] in V:\Xamarin\MvvmCross\MvvmCross\Platform\Platform\Core\MvxDelegateExtensionMethods.cs:16 
  at MvvmCross.Platform.iOS.Views.MvxEventSourceViewController.ViewDidLoad () [0x00006] in V:\Xamarin\MvvmCross\MvvmCross\Platform\iOS\Views\MvxEventSourceViewController.cs:63