Merge pull request #10939 from ahocevar/event-type

Losen listener type

src/ol/Observable.js

@@ -49,7 +49,7 @@ class Observable extends EventTarget {
   /**
    * Listen for a certain type of event.
    * @param {string|Array<string>} type The event type or array of event types.
-   * @param {import("./events.js").ListenerFunction} listener The listener function.
+   * @param {function(?): ?} listener The listener function.
    * @return {import("./events.js").EventsKey|Array<import("./events.js").EventsKey>} Unique key for the listener. If
    *     called with an array of event types as the first argument, the return
    *     will be an array of keys.