Fix generator bug with nested delegate types (#376)

Author: jasongin

src/NodeApi.Generator/ModuleGenerator.cs

@@ -395,6 +395,7 @@ private void ExportModule(
         }
 
         // Generate adapters for exported delegates for later use in method marshalling.
+        // Delegate types are not exported as properties, only as marshalling adapters.
         foreach (ITypeSymbol exportDelegate in exportItems.OfType<ITypeSymbol>()
             .Where((t) => t.TypeKind == TypeKind.Delegate))
         {
@@ -659,8 +660,10 @@ private void ExportMembers(
             {
                 s += $".AddProperty(\"{field.Name}\", {field.ConstantValue}, {propertyAttributes})";
             }
-            else if (member is INamedTypeSymbol nestedType)
+            else if (member is INamedTypeSymbol nestedType &&
+                nestedType.TypeKind != TypeKind.Delegate)
             {
+                // Delegate types are not exported as properties, only as marshalling adapters.
                 string nestedTypeVariableName = "type_" + GetFullName(nestedType).Replace('.', '_');
                 s += $".AddProperty(\"{GetExportName(nestedType)}\", {nestedTypeVariableName}, " +
                     $"{propertyAttributes})";

test/TestCases/napi-dotnet/Delegates.cs

@@ -15,6 +15,8 @@ namespace Microsoft.JavaScript.NodeApi.TestCases;
 [JSExport]
 public static class Delegates
 {
+    public delegate string NestedDelegate(string value);
+
     public static void CallAction(Action<int> actionDelegate, int value) => actionDelegate(value);
 
     public static int CallFunc(Func<int, int> funcDelegate, int value) => funcDelegate(value);