Mishandling of resources

ParseFile.cs

// Excerpt from https://blogs.msdn.microsoft.com/seteplia/2018/09/05/combining-iterator-blocks-and-async-methods-in-c/

public static IEnumerable<Task<int>> ParseFile(string path)
{
    if (string.IsNullOrEmpty(path)) { throw new ArgumentNullException(nameof(path)); }

    // OpenWithRetryPolicyAsync uses RetryPolicy to try to open the file more than once.
    // The method throws FileNotFoundException if the file does not exists.
    using (var file = OpenWithRetryPolicyAsync(path).Result)
    {
        using (var reader = new StreamReader(file))
        {
            // Let's assume that the first line contains a number of entries.

            // Using int.Parse for simplicities sake
            var numberOfEntries = int.Parse(reader.ReadLine());

            for (int entry = 0; entry < numberOfEntries; entry++)
            {
                yield return ReadAndParseAsync(reader);
            }
        }
    }
}

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