refactor: allow async event listeners

- https://github.com/EventEmitter2/EventEmitter2/tree/v6.4.9#emitteronevent-listener-options-objectboolean

Signed-off-by: Lexus Drumgold <[email protected]>

Author: unicornware

README.md

@@ -2556,7 +2556,7 @@ Handle an `event` (TypeScript type).
 ```ts
 type KronkEventListener<T extends KronkEvent = KronkEvent> = (
   event: T
-) => undefined
+) => Awaitable<undefined>
 ```
 
 #### Type Parameters

src/lib/command.mts

@@ -85,7 +85,7 @@ import {
   reduceRight
 } from '@flex-development/tutils'
 import { ok } from 'devlop'
-import EventEmitter, { type OnOptions } from 'eventemitter2'
+import EventEmitter, { type ListenerFn, type OnOptions } from 'eventemitter2'
 import plur from 'plur'
 
 /**
@@ -2544,7 +2544,7 @@ class Command extends Helpable {
     listener: KronkEventListener<T>,
     options?: OnOptions | boolean | undefined
   ): undefined {
-    return void this.events.on(event, listener, options)
+    return void this.events.on(event, listener as ListenerFn, options)
   }
 
   /**

src/types/__tests__/kronk-event-listener.spec-d.mts

@@ -4,7 +4,7 @@
  */
 
 import type TestSubject from '#types/kronk-event-listener'
-import type { OptionEvent } from '@flex-development/kronk'
+import type { Awaitable, OptionEvent } from '@flex-development/kronk'
 
 describe('unit-d:types/KronkEventListener', () => {
   type T = OptionEvent
@@ -17,8 +17,8 @@ describe('unit-d:types/KronkEventListener', () => {
   })
 
   describe('returns', () => {
-    it('should return undefined', () => {
-      expectTypeOf<Subject>().returns.toEqualTypeOf<undefined>()
+    it('should return Awaitable<undefined>', () => {
+      expectTypeOf<Subject>().returns.toEqualTypeOf<Awaitable<undefined>>()
     })
   })
 })

src/types/kronk-event-listener.mts

@@ -3,22 +3,23 @@
  * @module kronk/types/KronkEventListener
  */
 
-import type { KronkEvent } from '@flex-development/kronk'
+import type { Awaitable, KronkEvent } from '@flex-development/kronk'
 
 /**
  * Handle an `event`.
  *
+ * @see {@linkcode Awaitable}
  * @see {@linkcode KronkEvent}
  *
  * @template {KronkEvent} [T=KronkEvent]
  *  The emitted event
  *
  * @param {KronkEvent} event
  *  The emitted event
- * @return {undefined}
+ * @return {Awaitable<undefined>}
  */
 type KronkEventListener<T extends KronkEvent = KronkEvent> = (
   event: T
-) => undefined
+) => Awaitable<undefined>
 
 export type { KronkEventListener as default }