UriFormatException: Invalid URI: The URI is empty.
StackTrace:
   at System.Uri.CreateThis(String uri, Boolean dontEscape, UriKind uriKind)
   at DynamicClass.cc.<>c__DisplayClass140.<<初始化>b__11a>d__207.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)