Fix #1706: Handle unloaded projects correctly to avoid NotImplementedException

ILSpy.AddIn/Commands/OpenILSpyCommand.cs

@@ -98,16 +98,25 @@ namespace ICSharpCode.ILSpy.AddIn.Commands
 		protected EnvDTE.Project FindProject(IEnumerable<EnvDTE.Project> projects, string projectFile)
 		{
 			foreach (var project in projects) {
-				if (project.Kind == DTEConstants.vsProjectKindSolutionItems) {
+				switch (project.Kind) {
+					case DTEConstants.vsProjectKindSolutionItems:
 						// This is a solution folder -> search in sub-projects
 						var subProject = FindProject(
 							project.ProjectItems.OfType<EnvDTE.ProjectItem>().Select(pi => pi.SubProject).OfType<EnvDTE.Project>(),
 							projectFile);
 						if (subProject != null)
 							return subProject;
-				} else {
+						break;
+
+					case DTEConstants.vsProjectKindUnmodeled:
+						// Skip unloaded projects completely
+						break;
+
+					default:
+						// Match by project's file name
 						if (project.FileName == projectFile)
 							return project;
+						break;
 				}
 			}