C# AsyncStateMachine Decompile

I have nearly working code but OnRequest method is full of errors, I see that it's compiled code I think. Any help to make this code into human readable code?

[AsyncStateMachine(typeof(Service1.<OnRequest>d__24))]
public Task OnRequest(object sender, SessionEventArgs e)
{
    Service1.<OnRequest>d__24 <OnRequest>d__;
    <OnRequest>d__.<>4__this = this;
    <OnRequest>d__.e = e;
    <OnRequest>d__.<>t__builder = AsyncTaskMethodBuilder.Create();
    <OnRequest>d__.<>1__state = -1;
    AsyncTaskMethodBuilder <>t__builder = <OnRequest>d__.<>t__builder;
    <>t__builder.Start<Service1.<OnRequest>d__24>(ref <OnRequest>d__);
    return <OnRequest>d__.<>t__builder.Task;
}

Or I'm helpless here, I don't know what is that and I would like explanation in worst case if I can't have solution for this.