Handle case where SolutionName is not set (or set to *Undefined*)

Fixes #32

Author: CZEMacLeod

src/C3D/Extensions/Aspire/IISExpress/IISEndPointConfigurator.cs

@@ -28,7 +28,7 @@ public IISEndPointConfigurator(DistributedApplicationModel appModel,
 
     public void Configure()
     {
-        var appHostConfig = options.Value.ApplicationHostConfig!;
+        var appHostConfig = options.Value.ApplicationHostConfig ?? ApplicationHostConfigurationExtensions.GetTempConfigFile();
         foreach (var project in appModel.Resources.OfType<IISExpressProjectResource>())
         {
             try

src/C3D/Extensions/Aspire/IISExpress/IISExpressOptions.cs

@@ -89,7 +89,12 @@ public IEnumerable<ValidationResult> Validate(ValidationContext validationContex
         return results;
     }
 
-    public string? ApplicationHostConfig => SolutionDir is null || SolutionName is null ? null :
+    public string? ApplicationHostConfig => 
+        (string.IsNullOrEmpty(SolutionDir) || 
+            (string.IsNullOrEmpty(SolutionName) ||
+                SolutionName.IndexOfAny(Path.GetInvalidFileNameChars())!=-1
+            )
+        ) ? null :
         System.IO.Path.Combine(
             SolutionDir,
             ".vs",