Read lines from more than 1 file of different file extensions, extract the data and output to screen

Question

Hi,
I am trying to read data from more than one file at once. The files are different types e.g. one is a text file one is an xml file like so, StudentInformation.txt, CollegeInformation.xml. The files are all stored in one place, in this case on the D drive of
a local computer. I am trying to locate any files in the D drive with a file extension of .txt or of .xml (there may be more than two of these files in the future, so I'm trying to allow for that). Then I want to open all of these files, extract the information
and output all the information in one display window. I want all the information from these two or more files to be displayed together in the display window.
Here is the code so far. It is throwing up errors.
        //Load from txt or xml files
        private void btnLoad_Click(object sender, RoutedEventArgs e)
                IEnumerable<string> fileContents = Directory.EnumerateFiles("D:\\", "*.*", SearchOption.TopDirectoryOnly)
                .Select(x => new FileInfo(x))
                .Where(x => x.Extension == ".xml" || x.Extension == ".txt")
                .Select(file => ParseFile(file));}
                private string ParseFile(FileInfo file)
                    try
                        using (StreamReader sr = new StreamReader(file.FullName))
                            string line;
                            while ((line = sr.ReadLine()) != null)
                                //Logic here to determine if this is the correct file and append accordingly
                                lbDisplay.Items.Add(line);
                            return line;
                    catch (Exception ex)
                        // Let the user know what went wrong
                        MessageBox.Show("The file could not be read: ");
                        MessageBox.Show(ex.Message);
The error it throws up is:
Error 1
'BookList.MainWindow.ParseFile(System.IO.FileInfo)': not all code paths return a value

Answer 1

This is the Small Basic programming language so moving to a C# forum.
But you need all paths to return a value, including if an exception is called and it jumps to the catch, perhaps just:
// Let the user know what went wrong
MessageBox.Show("The file could not be read: ");
MessageBox.Show(ex.Message);
return "";