dotnet
CommandHandler.GetExitCodeAsync only awaits Task<int> return types
I believe it would make sense that GetExitCodeAsync:
https://github.com/dotnet/command-line-api/blob/a0782c85fd8f7aed16f46935998e9280c86ed2fb/src/System.CommandLine.NamingConventionBinder/CommandHandler.cs#L607
Should await any return object that is a descendant of the Task type. If the type is Task<int> the int value should be returned, otherwise, return 0.
As it stands, an asynchronous method used as a command handler that does not return an int is unlikely to run to completion if the System.CommandLine.Hosting code is used.
This can be seen easily in:
https://github.com/dotnet/command-line-api/blob/a0782c85fd8f7aed16f46935998e9280c86ed2fb/samples/HostingPlayground/Program.cs#L36
by adding an await Task.Delay(TimeSpan.FromSeconds(10)); to force the Run method to yield.
Overall I don't like checking whether the dynamic type of the return value is Task or Task<int>. This can break if a handler is declared to return Task but is not async and gets the Task from code that returns a Task<int> as an implementation detail. I'd rather see ModelBindingCommandHandler check the static return type of _handlerMethodInfo or _handlerDelegate.
