Resource handling with combined enumerable and Task-based deferred execution, ensuring correct sequencing

EnumerableTaskDeferralResourceHandlingFixed.cs

public static IEnumerable<Task<int>> ParseFile(string path)
{
    using (var reader = new StreamReader(path))
    {
        while (!reader.EndOfStream)
        {
            Task<int> readLineTask = null;
            try
            {
                readLineTask = ReadAndParseAsync(reader);
                yield return readLineTask;
            }
            finally
            {
                // There are three ways we can end up here:
                //  1) an exception occurred (in which case readLineTask may still be null)
                //  2) The caller asked for the next item (in which case execution will resume
                //      from the yield return, and we'll try another loop iteration
                //  3) The caller has decided to stop early, calling Dispose on the enumerator
                //      before reaching the end
                // If it's either 2 or 3 (i.e., we have a non-null readLineTask), we need to ensure
                // that the last task we created is complete. (In case 2, we need it to be complete
                // because we can't test for EndOfStream, nor can we go on to begin another read until
                // the last read finishes. In case 3, we need to ensure that the read completes before
                // we dispose the StreamReader.)
                // Hopefully the caller already awaited the task for us. But if they didn't we need to
                // block now until it completes.
                if (readLineTask?.IsCompleted == false)
                {
                    // Calling Wait is almost always a terrible idea. But we've been
                    // forced into this by the mismatch between our return type, and the
                    // nature of the work we're doing.
                    readLineTask.Wait();
                }
            }
        }
    }
}

private static async Task<int> ReadAndParseAsync(StreamReader reader)
{
    string line = await reader.ReadLineAsync().ConfigureAwait(false);
    return int.Parse(line);
}