Fix: mistake in auto assigning Pixel ID from config

Author: NielsCodes

projects/pixel/src/lib/pixel.service.ts

@@ -45,7 +45,7 @@ export class PixelService {
    * - Adds the script to page's head
    * - Tracks first page view
    */
-  initialize(pixelId?: string): void {
+  initialize(pixelId = this.config.pixelId): void {
     if (this.isLoaded()) {
       console.warn('Tried to initialize a Pixel instance while another is already active. Please call `remove()` before initializing a new instance.');
       return;