Made error registry on Server public (#32)

Author: zefir-git

src/Server.ts

@@ -16,7 +16,11 @@ class Server {
     public readonly routes = new RouteRegistry();
     private readonly server: http.Server;
     private readonly copyOrigin: boolean;
-    private readonly errors = new ServerErrorRegistry();
+
+    /**
+     * This server's error registry.
+     */
+    public readonly errors = new ServerErrorRegistry();
 
     /**
      * Create a new HTTP server.