Feat 1179 race issue with play verb (#1183)

* Fixed race issue between queueCommand false and queueCommand true when play task is involved

https://github.com/jambonz/jambonz-feature-server/issues/1179

* removed unnecessary emitter

* added destroy mechanism for stickyEventEmitter

* clearing stickyEventEmitter

* memory leak fix

lib/utils/sticky-event-emitter.js

@@ -0,0 +1,70 @@
+const EventEmitter = require('events');
+
+/**
+ * A specialized EventEmitter that caches the most recent event emissions.
+ * When new listeners are added, they immediately receive the most recent
+ * event if it was previously emitted. This is useful for handling state
+ * changes where late subscribers need to know the current state.
+ *
+ * Features:
+ * - Caches the most recent emission for each event type
+ * - New listeners immediately receive the cached event if available
+ * - Supports both regular (on) and one-time (once) listeners
+ * - Maintains compatibility with Node's EventEmitter interface
+ */
+class StickyEventEmitter extends EventEmitter {
+  constructor() {
+    super();
+    this._eventCache = new Map();
+    this._onceListeners = new Map(); // For storing once listeners if needed
+  }
+  destroy() {
+    this._eventCache.clear();
+    this._onceListeners.clear();
+    this.removeAllListeners();
+  }
+  emit(event, ...args) {
+    // Store the event and its args
+    this._eventCache.set(event, args);
+
+    // If there are any 'once' listeners waiting, call them
+    if (this._onceListeners.has(event)) {
+      const listeners = this._onceListeners.get(event);
+      for (const listener of listeners) {
+        listener(...args);
+      }
+      if (this.onSuccess) {
+        this.onSuccess();
+      }
+      this._onceListeners.delete(event);
+    }
+
+    return super.emit(event, ...args);
+  }
+
+  on(event, listener) {
+    if (this._eventCache.has(event)) {
+      listener(...this._eventCache.get(event));
+    }
+    return super.on(event, listener);
+  }
+
+  once(event, listener) {
+    if (this._eventCache.has(event)) {
+      listener(...this._eventCache.get(event));
+      if (this.onSuccess) {
+        this.onSuccess();
+      }
+    } else {
+      // Store listener in case emit comes before
+      if (!this._onceListeners.has(event)) {
+        this._onceListeners.set(event, []);
+      }
+      this._onceListeners.get(event).push(listener);
+      super.once(event, listener); // Also attach to native once
+    }
+    return this;
+  }
+}
+
+module.exports = StickyEventEmitter;