diff --git a/package-lock.json b/package-lock.json
index 6cfcb7f..a8181f3 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,15 +1,15 @@
 {
 	"name": "api-machine",
-	"version": "1.0.0",
+	"version": "1.0.1",
 	"lockfileVersion": 3,
 	"requires": true,
 	"packages": {
 		"": {
 			"name": "api-machine",
-			"version": "1.0.0",
+			"version": "1.0.1",
 			"license": "MIT",
 			"dependencies": {
-				"auto-oas": "^1.2.0",
+				"auto-oas": "^1.2.1",
 				"cors": "^2.8.5",
 				"express": "^5.1.0",
 				"swagger-ui-express": "^5.0.1",
@@ -1649,9 +1649,9 @@
 			}
 		},
 		"node_modules/auto-oas": {
-			"version": "1.2.0",
-			"resolved": "https://registry.npmjs.org/auto-oas/-/auto-oas-1.2.0.tgz",
-			"integrity": "sha512-WWn5Zv2Ebo9NJTlKnExnBF7O/bK2jhZTnp4VnMnZ4E4o7Wyv7uhvbuWDhbbkeo9h456pkfWkeRrG5D2x6Xk/ig==",
+			"version": "1.2.1",
+			"resolved": "https://registry.npmjs.org/auto-oas/-/auto-oas-1.2.1.tgz",
+			"integrity": "sha512-eqfKTC60L4UHebdpX8uF5zDjVkrblpUGX01O8PW7IjUSdtFRvnZ354bBW/9dE7SAKeYzj/cOZlJCN+Emea8siw==",
 			"license": "MIT",
 			"dependencies": {
 				"valsan": "^2.1.0"
diff --git a/package.json b/package.json
index dfe6e0a..7002941 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "api-machine",
-	"version": "1.0.0",
+	"version": "1.0.1",
 	"description": "api-machine",
 	"private": "true",
 	"typescript-template": {
@@ -22,7 +22,7 @@
 		"publish": "npm run script -- publish"
 	},
 	"dependencies": {
-		"auto-oas": "^1.2.0",
+		"auto-oas": "^1.2.1",
 		"cors": "^2.8.5",
 		"express": "^5.1.0",
 		"swagger-ui-express": "^5.0.1",
diff --git a/src/error/http-errors/http-error.ts b/src/error/http-errors/http-error.ts
index efe7703..7d5cdcb 100644
--- a/src/error/http-errors/http-error.ts
+++ b/src/error/http-errors/http-error.ts
@@ -5,6 +5,7 @@ import { HttpErrorOptions } from '../error-options';
  * All HTTP errors extend from this class
  */
 export abstract class HTTPError extends Error {
+	public isApiMachineError = true;
 	public readonly options: HttpErrorOptions = {};
 	public readonly timestamp = new Date().toISOString();
 
diff --git a/src/oas/oas-rest-server-converter.ts b/src/oas/oas-rest-server-converter.ts
index edac932..2d282b4 100644
--- a/src/oas/oas-rest-server-converter.ts
+++ b/src/oas/oas-rest-server-converter.ts
@@ -59,11 +59,11 @@ export class OasRestServerConverter {
 
 	public async convertRouter(router: BaseApiRouter) {
 		for (const route of router.registeredRoutes) {
-			if (route instanceof BaseApiEndpoint) {
-				await this.convertEndpoint(route);
+			if (route.routeType === 'endpoint') {
+				await this.convertEndpoint(route as BaseApiEndpoint);
 			}
-			else if (route instanceof BaseApiRouter) {
-				await this.convertRouter(route);
+			else if (route.routeType === 'router') {
+				await this.convertRouter(route as BaseApiRouter);
 			}
 		}
 	}
diff --git a/src/router/base.ts b/src/router/base.ts
index bf37b81..3d04d04 100644
--- a/src/router/base.ts
+++ b/src/router/base.ts
@@ -6,6 +6,7 @@ export abstract class BaseApiRoute {
 	public fullPath: string;
 	public name: string;
 	public description?: string;
+	public routeType: 'router' | 'endpoint';
 
 	/**
 	 * Optional array of Express middleware to apply
diff --git a/src/router/endpoint.ts b/src/router/endpoint.ts
index 1c14627..400925e 100644
--- a/src/router/endpoint.ts
+++ b/src/router/endpoint.ts
@@ -27,6 +27,7 @@ export enum EndpointMethod {
 }
 
 export abstract class BaseApiEndpoint extends BaseApiRoute {
+	override routeType = 'endpoint' as const;
 	override path = '';
 	public tag?: string;
 	public method: EndpointMethod = EndpointMethod.GET;
diff --git a/src/router/router.ts b/src/router/router.ts
index 8a398ae..ef9bfdd 100644
--- a/src/router/router.ts
+++ b/src/router/router.ts
@@ -3,6 +3,7 @@ import { ApiRoute, BaseApiRoute } from './base';
 import { BaseApiEndpoint, EndpointMethod } from './endpoint';
 
 export abstract class BaseApiRouter extends BaseApiRoute {
+	override routeType = 'router' as const;
 	protected router: ExpressRouter;
 
 	public registeredRoutes: BaseApiRoute[] = [];
@@ -45,8 +46,8 @@ export abstract class BaseApiRouter extends BaseApiRoute {
 			// Set parent relationship for authentication cascading
 			instance.parentRoute = this;
 
-			if (instance instanceof BaseApiEndpoint) {
-				instance.tag = tag;
+			if (instance.routeType === 'endpoint') {
+				(instance as BaseApiEndpoint).tag = tag;
 			}
 
 			await instance.register(this.router, this.fullPath);
@@ -54,14 +55,16 @@ export abstract class BaseApiRouter extends BaseApiRoute {
 			this.registeredRoutes.push(instance);
 
 			// Track endpoint methods for 405 handling
-			if (instance instanceof BaseApiEndpoint) {
+			if (instance.routeType === 'endpoint') {
 				const path = instance.path;
 
 				if (!pathMethods.has(path)) {
 					pathMethods.set(path, new Set());
 				}
 
-				pathMethods.get(path)!.add(instance.method);
+				pathMethods
+					.get(path)!
+					.add((instance as BaseApiEndpoint).method);
 			}
 		}
 
diff --git a/src/server/server.ts b/src/server/server.ts
index ff8dc49..c591592 100644
--- a/src/server/server.ts
+++ b/src/server/server.ts
@@ -174,15 +174,17 @@ export abstract class RestServer {
 				next: express.NextFunction
 			) => {
 				// Handle HTTPError instances
-				if (error instanceof HTTPError) {
+				if ((error as HTTPError).isApiMachineError) {
 					// Set custom headers if provided
-					Object.entries(error.headers).forEach(([key, value]) => {
-						response.setHeader(key, value);
-					});
+					Object.entries((error as HTTPError).headers).forEach(
+						([key, value]) => {
+							response.setHeader(key, value);
+						}
+					);
 
 					return response
-						.status(error.getStatusCode())
-						.json(error.getResponseJson());
+						.status((error as HTTPError).getStatusCode())
+						.json((error as HTTPError).getResponseJson());
 				}
 
 				if (