fix: include message and code on errors when logging in node.js a…

…nd deno

src/EventSource.ts

@@ -517,7 +517,7 @@ export class EventSource extends EventTarget {
    * @param code - The HTTP status code, if available
    * @internal
    */
-  #failConnection(error?: string, code?: number) {
+  #failConnection(message?: string, code?: number) {
     // [spec] …if the readyState attribute is set to a value other than CLOSED,
     // [spec] sets the readyState attribute to CLOSED…
     if (this.#readyState !== this.CLOSED) {
@@ -530,7 +530,7 @@ export class EventSource extends EventTarget {
     // [spec] > to their development consoles whenever an error event is fired, since little
     // [spec] > to no information can be made available in the events themselves.
     // Printing to console is not very programatically helpful, though, so we emit a custom event.
-    const errorEvent = new ErrorEvent('error', code, error)
+    const errorEvent = new ErrorEvent('error', {code, message})
 
     this.#onError?.(errorEvent)
     this.dispatchEvent(errorEvent)
@@ -539,11 +539,11 @@ export class EventSource extends EventTarget {
   /**
    * Schedules a reconnection attempt against the EventSource endpoint.
    *
-   * @param error - The error causing the connection to fail
+   * @param message - The error causing the connection to fail
    * @param code - The HTTP status code, if available
    * @internal
    */
-  #scheduleReconnect(error?: string, code?: number) {
+  #scheduleReconnect(message?: string, code?: number) {
     // [spec] If the readyState attribute is set to CLOSED, abort the task.
     if (this.#readyState === this.CLOSED) {
       return
@@ -553,7 +553,7 @@ export class EventSource extends EventTarget {
     this.#readyState = this.CONNECTING
 
     // [spec] Fire an event named `error` at the EventSource object.
-    const errorEvent = new ErrorEvent('error', code, error)
+    const errorEvent = new ErrorEvent('error', {code, message})
     this.#onError?.(errorEvent)
     this.dispatchEvent(errorEvent)
 

src/errors.ts

@@ -22,10 +22,58 @@ export class ErrorEvent extends Event {
    */
   public message?: string | undefined
 
-  constructor(type: string, code?: number, message?: string) {
+  /**
+   * Constructs a new `ErrorEvent` instance. This is typically not called directly,
+   * but rather emitted by the `EventSource` object when an error occurs.
+   *
+   * @param type - The type of the event (should be "error")
+   * @param errorEventInitDict - Optional properties to include in the error event
+   */
+  constructor(
+    type: string,
+    errorEventInitDict?: {message?: string | undefined; code?: number | undefined},
+  ) {
     super(type)
-    this.code = code ?? undefined
-    this.message = message ?? undefined
+    this.code = errorEventInitDict?.code ?? undefined
+    this.message = errorEventInitDict?.message ?? undefined
+  }
+
+  /**
+   * Node.js "hides" the `message` and `code` properties of the `ErrorEvent` instance,
+   * when it is `console.log`'ed. This makes it harder to debug errors. To ease debugging,
+   * we explicitly include the properties in the `inspect` method.
+   *
+   * This is automatically called by Node.js when you `console.log` an instance of this class.
+   *
+   * @param _depth - The current depth
+   * @param options - The options passed to `util.inspect`
+   * @param inspect - The inspect function to use (prevents having to import it from `util`)
+   * @returns A string representation of the error
+   */
+  [Symbol.for('nodejs.util.inspect.custom')](
+    _depth: number,
+    options: {colors: boolean},
+    inspect: (obj: unknown, inspectOptions: {colors: boolean}) => string,
+  ): string {
+    return inspect(inspectableError(this), options)
+  }
+
+  /**
+   * Deno "hides" the `message` and `code` properties of the `ErrorEvent` instance,
+   * when it is `console.log`'ed. This makes it harder to debug errors. To ease debugging,
+   * we explicitly include the properties in the `inspect` method.
+   *
+   * This is automatically called by Deno when you `console.log` an instance of this class.
+   *
+   * @param inspect - The inspect function to use (prevents having to import it from `util`)
+   * @param options - The options passed to `Deno.inspect`
+   * @returns A string representation of the error
+   */
+  [Symbol.for('Deno.customInspect')](
+    inspect: (obj: unknown, inspectOptions: {colors: boolean}) => string,
+    options: {colors: boolean},
+  ): string {
+    return inspect(inspectableError(this), options)
   }
 }
 
@@ -73,3 +121,21 @@ export function flattenError(err: unknown): string {
 
   return err.message
 }
+
+/**
+ * Convert an `ErrorEvent` instance into a plain object for inspection.
+ *
+ * @param err - The `ErrorEvent` instance to inspect
+ * @returns A plain object representation of the error
+ * @internal
+ */
+function inspectableError(err: ErrorEvent) {
+  return {
+    type: err.type,
+    message: err.message,
+    code: err.code,
+    defaultPrevented: err.defaultPrevented,
+    cancelable: err.cancelable,
+    timeStamp: err.timeStamp,
+  }
+}