fix(gen): properly handle recursive schemas

internal/gen/schema.go

@@ -51,7 +51,18 @@ func mkEnumOgenSchema(ed protoreflect.EnumDescriptor) *ogen.Schema {
 }
 
 func (g *Generator) mkSchema(msg *protogen.Message) error {
-	s := ogen.NewSchema().SetType("object")
+	name := descriptorName(msg.Desc)
+	if g.hasDescriptorName(name) {
+		return nil
+	}
+	g.setDescriptorName(name)
+
+	s := ogen.NewSchema()
+	{
+		g.spec.AddSchema(name, s)
+		g.messages[name] = msg
+	}
+	s.SetType("object")
 
 	if err := g.mkJSONFields(s, msg.Fields); err != nil {
 		return err
@@ -62,22 +73,13 @@ func (g *Generator) mkSchema(msg *protogen.Message) error {
 			continue
 		}
 
-		if field.Message != nil {
-			name := descriptorName(field.Desc)
-			if g.hasDescriptorName(name) {
-				s.SetRef(descriptorRef(field.Message.Desc))
-
-				continue
-			}
-
-			g.setDescriptorName(name)
-
-			if err := g.mkSchema(field.Message); err != nil {
+		if fmsg := field.Message; fmsg != nil {
+			if err := g.mkSchema(fmsg); err != nil {
 				return err
 			}
 		}
-		if field.Enum != nil {
-			g.mkEnum(field.Enum)
+		if enum := field.Enum; enum != nil {
+			g.mkEnum(enum)
 		}
 	}
 
@@ -91,9 +93,6 @@ func (g *Generator) mkSchema(msg *protogen.Message) error {
 		g.mkEnum(e)
 	}
 
-	name := descriptorName(msg.Desc)
-	g.spec.AddSchema(name, s)
-	g.messages[name] = msg
 	return nil
 }