Returning null from a non-async Task/Task<TResult> method will cause a
NullReferenceException at runtime if the method is awaited. This problem can be avoided by returning Task.CompletedTask or Task.FromResult<TResult>(null)
respectively.
public Task DoFooAsync()
{
return null; // Noncompliant: Causes a NullReferenceException if awaited.
}
public async Task Main()
{
await DoFooAsync(); // NullReferenceException
}
