[uapaot] Two CustomChannelTests Failed due to NullReferenceException

[shmao]

CustomChannelTest.CustomChannel_Async_Request_Exception_Propagates [FAIL]
System.NullReferenceException : Object reference not set to an instance of an object.
               Stack Trace:
                  c:\oss\wcf\src\System.Private.ServiceModel\src\System\ServiceModel\Channels\ServiceChannelProxy.cs(260,0): at System.ServiceModel.Channels.ServiceChannelProxy.TaskCompletionSourceProxy.get_Task()
                  c:\oss\wcf\src\System.Private.ServiceModel\src\System\ServiceModel\Channels\ServiceChannelProxy.cs(205,0): at System.ServiceModel.Channels.ServiceChannelProxy.TaskCreator.CreateGenericTask($ServiceChannel channel, $ProxyOperationRuntime operation, Object[] inputParameters)
                  c:\oss\wcf\src\System.Private.ServiceModel\src\System\ServiceModel\Channels\ServiceChannelProxy.cs(166,0): at System.ServiceModel.Channels.ServiceChannelProxy.TaskCreator.CreateTask($ServiceChannel channel, $MethodCall methodCall, $ProxyOperationRuntime operation)
                  c:\oss\wcf\src\System.Private.ServiceModel\src\System\ServiceModel\Channels\ServiceChannelProxy.cs(147,0): at System.ServiceModel.Channels.ServiceChannelProxy.Invoke(MethodInfo targetMethod, Object[] args)
                  C:\Users\shmao\AppData\Local\Temp\Ilc196519191\xunit.console.netcore.ITFProxy\xunit.console.netcore.ITFProxy.g.cs(38,0): at __InterfaceProxies.ServiceChannelProxy_ICustomChannelServiceInterface.CustomChannelTest_P.ICustomChannelServiceInterface_P.ProcessAsync($Message input)
                  c:\oss\wcf\src\System.ServiceModel.Primitives\tests\Channels\CustomChannelTest.cs(297,0): at CustomChannelTest.CustomChannel_Async_Request_Exception_Propagates()
                     at _$ILCT$.$ILT$ReflectionDynamicInvoke$.InvokeRetV(Object thisPtr, IntPtr methodToCall, ArgSetupState argSetupState, Boolean targetIsThisCall)
                     at System.InvokeUtils.CalliIntrinsics.Call(IntPtr dynamicInvokeHelperMethod, Object thisPtr, IntPtr methodToCall, ArgSetupState argSetupState, Boolean isTargetThisCall)
                  f:\dd\ndp\fxcore\CoreRT\src\System.Private.CoreLib\src\System\InvokeUtils.cs(400,0): at System.InvokeUtils.CallDynamicInvokeMethod(Object thisPtr, IntPtr methodToCall, Object thisPtrDynamicInvokeMethod, IntPtr dynamicInvokeHelperMethod, IntPtr dynamicInvokeHelperGenericDictionary, Object targetMethodOrDelegate, Object[] parameters, BinderBundle binderBundle, Boolean invokeMethodHelperIsThisCall, Boolean methodToCallIsThisCall)

CustomChannelTest.CustomChannel_Async_Open_Close_Methods_Called [FAIL]
               System.NullReferenceException : Object reference not set to an instance of an object.
               Stack Trace:
                  c:\oss\wcf\src\System.Private.ServiceModel\src\System\ServiceModel\Channels\ServiceChannelProxy.cs(260,0): at System.ServiceModel.Channels.ServiceChannelProxy.TaskCompletionSourceProxy.get_Task()
                  c:\oss\wcf\src\System.Private.ServiceModel\src\System\ServiceModel\Channels\ServiceChannelProxy.cs(205,0): at System.ServiceModel.Channels.ServiceChannelProxy.TaskCreator.CreateGenericTask($ServiceChannel channel, $ProxyOperationRuntime operation, Object[] inputParameters)
                  c:\oss\wcf\src\System.Private.ServiceModel\src\System\ServiceModel\Channels\ServiceChannelProxy.cs(166,0): at System.ServiceModel.Channels.ServiceChannelProxy.TaskCreator.CreateTask($ServiceChannel channel, $MethodCall methodCall, $ProxyOperationRuntime operation)
                  c:\oss\wcf\src\System.Private.ServiceModel\src\System\ServiceModel\Channels\ServiceChannelProxy.cs(147,0): at System.ServiceModel.Channels.ServiceChannelProxy.Invoke(MethodInfo targetMethod, Object[] args)
                  C:\Users\shmao\AppData\Local\Temp\Ilc196519191\xunit.console.netcore.ITFProxy\xunit.console.netcore.ITFProxy.g.cs(38,0): at __InterfaceProxies.ServiceChannelProxy_ICustomChannelServiceInterface.CustomChannelTest_P.ICustomChannelServiceInterface_P.ProcessAsync($Message input)
                  c:\oss\wcf\src\System.ServiceModel.Primitives\tests\Channels\CustomChannelTest.cs(158,0): at CustomChannelTest.CustomChannel_Async_Open_Close_Methods_Called()
                     at _$ILCT$.$ILT$ReflectionDynamicInvoke$.InvokeRetV(Object thisPtr, IntPtr methodToCall, ArgSetupState argSetupState, Boolean targetIsThisCall)
                     at System.InvokeUtils.CalliIntrinsics.Call(IntPtr dynamicInvokeHelperMethod, Object thisPtr, IntPtr methodToCall, ArgSetupState argSetupState, Boolean isTargetThisCall)
                  f:\dd\ndp\fxcore\CoreRT\src\System.Private.CoreLib\src\System\InvokeUtils.cs(400,0): at System.InvokeUtils.CallDynamicInvokeMethod(Object thisPtr, IntPtr methodToCall, Object thisPtrDynamicInvokeMethod, IntPtr dynamicInvokeHelperMethod, IntPtr dynamicInvokeHelperGenericDictionary, Object targetMethodOrDelegate, Object[] parameters, BinderBundle binderBundle, Boolean invokeMethodHelperIsThisCall, Boolean methodToCallIsThisCall)