function method1()
{
       method2();
}

async Task<ResultObj> function method2()
{
       //略
}

   public static void Main()
   {
      var task1 = Task.Run( () => { throw new CustomException("This exception is expected!"); } );

      try
      {
          task1.Wait();
      }
      catch (AggregateException ae)
      {
          foreach (var e in ae.InnerExceptions) {
              // Handle the custom exception.
              if (e is CustomException) {
                  Console.WriteLine(e.Message);
              }
              // Rethrow any other exception.
              else {
                  throw;
              }
          }
      }
   }

Task listenerTask = Task.Run(() => proxy.callService<ResultObject>(inputObj)).ContinueWith( 
	t => { logException(t, proxy.ServiceName); }, TaskContinuationOptions.OnlyOnFaulted);

private static void logException(Task<BaseAddOutput> t, string serviceName)
{
	var message = string.Empty;
    if (t.Exception != null)
       message = t.Exception.Message;
    if (t.Exception.InnerException != null)
       message = t.Exception.InnerException.Message;
    Debug.Log(ConfigUtil.GetBoolean("Debug"), "system call " + serviceName + " error, msg:" + message);
}