feat: add ErrorEvent polyfill for Node.js

deno.json

@@ -1,6 +1,6 @@
 {
   "name": "@oak/acorn",
-  "version": "0.6.0-alpha.1",
+  "version": "0.6.0-alpha.2",
   "exports": {
     ".": "./mod.ts",
     "./context": "./context.ts",

polyfills.ts

@@ -0,0 +1,54 @@
+// Copyright 2022-2024 the oak authors. All rights reserved.
+
+/**
+ * Node.js does not have the web standard {@linkcode ErrorEvent} and acorn
+ * extends it for router error events, so we need to polyfill it.
+ *
+ * @module
+ */
+
+if (!("ErrorEvent" in globalThis)) {
+  class ErrorEvent extends Event {
+    #message: string;
+    #filename: string;
+    #lineno: number;
+    #colno: number;
+    // deno-lint-ignore no-explicit-any
+    #error: any;
+
+    get message(): string {
+      return this.#message;
+    }
+    get filename(): string {
+      return this.#filename;
+    }
+    get lineno(): number {
+      return this.#lineno;
+    }
+    get colno(): number {
+      return this.#colno;
+    }
+    // deno-lint-ignore no-explicit-any
+    get error(): any {
+      return this.#error;
+    }
+
+    constructor(type: string, eventInitDict: ErrorEventInit = {}) {
+      super(type, eventInitDict);
+      const { message = "error", filename = "", lineno = 0, colno = 0, error } =
+        eventInitDict;
+      this.#message = message;
+      this.#filename = filename;
+      this.#lineno = lineno;
+      this.#colno = colno;
+      this.#error = error;
+    }
+  }
+
+  Object.defineProperty(globalThis, "ErrorEvent", {
+    value: ErrorEvent,
+    writable: true,
+    enumerable: false,
+    configurable: true,
+  });
+}

router.ts

@@ -60,6 +60,8 @@ import {
   responseFromHttpError,
 } from "./util.ts";
 
+import "./polyfills.ts";
+
 if (!("URLPattern" in globalThis)) {
   await import("npm:urlpattern-polyfill@10.0.0");
 }