public void OnError(Exception cause)
{
if (cause == null)
{
throw new ArgumentNullException(nameof(cause));
}
lock (this)
{
if (Volatile.Read(ref cancelled))
{
return;
}
if (done)
{
return;
}
done = true;
if (emitting)
{
error = cause;
return;
}
}
actual.OnError(cause);
}