T4 Templates builds with the 2017 version but fails with your 2022 version

[valeryan]

Hey, thanks for taking the time to rebuild this. I wanted to give it a try for a legacy project that still requires 2017. The extension installs but when I try to run a custom tool for template errors. It seems like some system information is not getting loaded. Here is a sample of the code that is failing to run:

public static void CalculateDatabaseConnectionString(ITextTemplatingEngineHost host)
	{
		DTE dte = (DTE)((IServiceProvider)host).GetService(typeof(SDTE));
		
		List<Project> projects = new List<Project>();
		
		try
		{
			foreach (var project in dte.Solution.Projects)
			{
				Project p = project as Project;
				// Skip test and misc projects
				if (p.Kind == "{67294A52-A4F0-11D2-AA88-00C04F688DDE}" || p.Kind == "66A26720-8FB5-11D2-AA7E-00C04F688DDE")
					continue;
				
				if (!p.Name.Contains("Curse.Cobalt"))
				{
					projects.Add(p);
				}
			}
		}
		catch (System.Runtime.Serialization.SerializationException)
		{
			// This is to skip projects that are a Database project
		}
		
		var solutionName = string.Empty;
		var regex = new Regex(@"(.*?\\)*(?<solutionName>.*?)\.sln", RegexOptions.Compiled);
		var match = regex.Match(dte.Solution.FullName);
		if(match != null && match.Groups != null && match.Groups.Count > 0)
		{
			solutionName = match.Groups["solutionName"].ToString();
		}

		var implementationProjects = !string.IsNullOrEmpty(solutionName) ? projects.Where(p => p.Name.StartsWith(solutionName)) : projects;
////////// Fails Here .//////
		var projectItem = implementationProjects
			.Where(project => project.ProjectItems != null)
			.SelectMany(project => project.ProjectItems.OfType<ProjectItem>())
			.Where(pi => pi.Name == "Cobalt.config")
			.First();
///////////////////////////////		
		string filename;
		try
		{
			filename = projectItem.get_FileNames(0);
		}
		catch
		{
			try
			{
				filename = projectItem.Document.FullName;
			}
			catch
			{
				throw new InvalidOperationException("Unable to calculate file path for Cobalt.config");
			}
		}
		
		var xml = XDocument.Load(filename);
		
		var database = xml
			.Elements("cobalt")
			.Single()
			.Elements("database")
			.Single();
		
		var activeKeyAtt = database.Attribute("activeKey");
		string activeKey;
		if (activeKeyAtt == null)
		{
			activeKey = "development";
		}
		else
		{
			activeKey = activeKeyAtt.Value;
		}
		var provider = database
			.Elements("databaseProvider")
			.Where(p => p.Attribute("key").Value == activeKey)
			.Single();
		
		string conn = provider.Attribute("connectionString").Value;
		if (string.IsNullOrEmpty(conn))
		{
			throw new InvalidOperationException("Cannot calculate connection string");
		}
		_connectionString = $"{conn}Connection Timeout=90;";

		string localConfigConnectionString = CalculateLocalConfigConnectionString(projects);

		if (localConfigConnectionString != null)
		{
			_connectionString = $"{localConfigConnectionString}Connection Timeout=90;";
		}
	}

When running this block in 2017 using the original T4toolbox it runs without issues but this code produces this in 2022 using this T4Toolbox

Error		Running transformation: System.InvalidOperationException: Sequence contains no elements
   at System.Linq.Enumerable.First[TSource](IEnumerable`1 source)

Do you have any thoughts if you are still around?