Fix AddCarter when DependencyContext is unavailable in single-file publish

src/Carter/CarterExtensions.cs

@@ -30,7 +30,7 @@
 
         foreach (var carterModuleInterface in builder.ServiceProvider.GetServices<ICarterModule>())
         {
             if (carterModuleInterface is CarterModule carterModule)
             {
                 var group = builder.MapGroup(carterModule.basePath);
 
@@ -281,7 +281,9 @@
         {
             validators = assemblies.SelectMany(ass => ass.GetTypes())
                 .Where(typeof(IValidator).IsAssignableFrom)
-                .Where(t => !t.GetTypeInfo().IsAbstract);
+                .Where(t =>
+                    !t.GetTypeInfo().IsAbstract &&
+                    !t.ContainsGenericParameters);  // skip open generic validators
 
             carterConfigurator.ValidatorTypes.AddRange(validators);
         }

src/Carter/DependencyContextAssemblyCatalog.cs

@@ -67,17 +67,29 @@ public virtual IReadOnlyCollection<Assembly> GetAssemblies()
             {
                 results.Add(overriddenAssembly);
             }
+
+            return results;
+        }
+
+        // DependencyContext is unavailable in single-file published apps.
+        // In that case, return the assemblies already loaded into the AppDomain.
+        if (this.dependencyContext is null)
+        {
+            foreach (var assembly in AppDomain.CurrentDomain.GetAssemblies())
+            {
+                results.Add(assembly);
+            }
+
+            return results;
         }
-        else
+
+        foreach (var library in this.dependencyContext.RuntimeLibraries)
         {
-            foreach (var library in this.dependencyContext.RuntimeLibraries)
+            if (IsReferencingCarter(library) || IsReferencingFluentValidation(library))
             {
-                if (IsReferencingCarter(library) || IsReferencingFluentValidation(library))
+                foreach (var assemblyName in library.GetDefaultAssemblyNames(this.dependencyContext))
                 {
-                    foreach (var assemblyName in library.GetDefaultAssemblyNames(this.dependencyContext))
-                    {
-                        results.Add(SafeLoadAssembly(assemblyName));
-                    }
+                    results.Add(SafeLoadAssembly(assemblyName));
                 }
             }
         }