refactor: Simplify and optimize event handling and listener management

lib/EventAPI-JS.js

@@ -7,7 +7,7 @@ const getPluginName = () => {
     } catch (error) {
         return error.stack.trim().match(/plugins\\(.*)\\.*\.js:[0-9]+\)$/i)?.[1] || "Unknown";
     }
-}
+};
 
 module.exports = {
     Event: {
@@ -37,6 +37,7 @@ module.exports = {
          */
         listen: function (eventName, callback) {
             try {
+                if (typeof callback !== "function") return false;
                 const eventReflection = {
                     onServerStopping: "ll::ServerStoppingEvent",
                     onClientLogin: "gmlib::ClientLoginAfterEvent",
@@ -75,6 +76,7 @@ module.exports = {
          * @returns {number}
          */
         emplaceListener: function (eventName, callback, priority = this.EventPriority.Normal, pluginName = getPluginName()) {
+            if (typeof callback !== "function") throw new Error("callback must be a function!");
             const /** @type {number} */ eventId = ll.imports("GMLIB_Event_API", "emplaceListener")(pluginName, eventName, priority);
             if (eventId === -1) throw new Error(`Event ${eventName} creation failed!`);
             ll.exports((...data) => {
@@ -83,7 +85,7 @@ module.exports = {
                     callback({
                         params: data,
                         cancel: () => result = true,
-                        setCancelled: (/** @type {boolean} */value) => result = value,
+                        setCancelled: (/** @type {boolean} */value) => { result = value; },
                         isCancelled: () => result,
                         getId: () => eventId,
                         getEventType: () => eventName
@@ -95,8 +97,7 @@ module.exports = {
                 }
                 return result;
             }, pluginName, eventName + "_" + eventId);
-            if (this.mEventData[eventName] === undefined) this.mEventData[eventName] = [];
-            this.mEventData[eventName].push(eventId);
+            (this.mEventData[eventName] ??= []).push(eventId);
             return eventId;
         },
 
@@ -140,7 +141,7 @@ module.exports = {
          * @param {string | undefined} eventName
          * @returns {number[] | Object.<string, number[]>}
          */
-        getListener: function(eventName) {
+        getListener: function (eventName) {
             return eventName === undefined ? this.mEventData : this.mEventData[eventName] ?? [];
         },