Its a warning and can be safely ignored. You said "It is not possible to ignore it, since it results in an unmanaged error and the application cannot continue" which makes no sense.
I try to help people out, this is not my job, this is open source code and I'm just helping out where I can.
I really think you should read more about async/await. I'm sure you'll have a eureka moment. The link I posted is to Stephen Toubs blog. He wrote a lot of blog posts on the subject and worked on async/await too. Also take a look on the Channel 9 website to learn more.
Hope that help!