Vulpix | Automated code grading system

        private async void btnClickThis_Click(object sender, EventArgs e)
    {
        //using example code from: https://docs.microsoft.com/en-us/dotnet/api/system.windows.forms.filedialog?view=windowsdesktop-6.0
        //to open a file dialog box and allow selection

        //variable declaration by section
        //file processing
        var fileContent = string.Empty;
        var filePath = string.Empty;
        //counting vowels and storing the word
        int vowelMax = 0;
        int vowelCount = 0;
        String maxVowels = "";
        //finding length and storing longest word
        int length = 0;
        int lengthMax = 0;
        String maxLength = "";
        //for storing first and last words alphabetically
        String first = "";
        String last = "";

        using (OpenFileDialog openFileDialog = new OpenFileDialog())
        {
            openFileDialog.InitialDirectory = "c:\\";
            openFileDialog.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*";
            openFileDialog.FilterIndex = 2;
            openFileDialog.RestoreDirectory = true;

            if (openFileDialog.ShowDialog() == DialogResult.OK)
            {
                //Get the path of specified file
                filePath = openFileDialog.FileName;

                //Read the contents of the file into a stream
                var fileStream = openFileDialog.OpenFile();
                using StreamWriter file = new("Stats.txt", append: true);
                using (StreamReader reader = new StreamReader(fileStream))
                {

                    do
                    {
                        //try catch in case file is null to begin with
                        try
                        {
                            //read one line at a time, converting it to lower case to start
                            fileContent = reader?.ReadLine()?.ToLower();
                            //split line into words, removing empty entries and separating by spaces
                            var words = fileContent?.Split(' ', StringSplitOptions.RemoveEmptyEntries);
                            if (words != null)
                            {
                                foreach (var word in words)
                                {
                                    //if the string is null, immediately store word
                                    //if word < first, store word as first
                                    if (first == null || String.Compare(word, first) < 0)
                                    {
                                        first = word;
                                    }
                                    //if the string is null, immediately store word
                                    //if word > last, store word as last
                                    else if (last == null || String.Compare(word, last) > 0)
                                    {
                                        last = word;
                                    }

                                    //find length of current word
                                    length = word.Length;
                                    //if len is greater than current max len, store new max len word
                                    if (length > lengthMax)
                                    {
                                        maxLength = word;
                                    }
                                    //iterate over each letter to check for vowels and total them up
                                    for (int i = 0; i < length; i++)
                                    {
                                        if (word[i] == 'a' || word[i] == 'e' || word[i] == 'i' || word[i] == 'o' || word[i] == 'u')
                                        {
                                            vowelCount++;
                                        }
                                    }
                                    //if vowelCount is greater than max, store word as new max
                                    if (vowelCount > vowelMax)
                                    {
                                        maxVowels = word;
                                    }
                                    await file.WriteLineAsync(word);
                                }
                            }
                        } catch (IOException error)
                        {
                            Console.WriteLine("IOException source: {0}", error.Source);
                        }
                    } while (fileContent != "");
                    //append file stats after processing is complete
                    await file.WriteLineAsync("First word(Alphabetically): " + first);
                    await file.WriteLineAsync("Last word(Alphabetically): " + last);
                    await file.WriteLineAsync("Longest word: " + maxLength);
                    await file.WriteLineAsync("Word with the most vowels: " + maxVowels);
                }
            }
        }
        MessageBox.Show(fileContent, "File Content at path: " + filePath, MessageBoxButtons.OK);
    }