Guard playlist code

Right now the playlist code is very raw.
It tries to do things, trusting JavaScript to fail in the right place.

:shrug:

index.php

@@ -3,7 +3,7 @@
  * Plugin Name: Media Playback Speed
  * Description: Appends playback buttons to the Media Player. Updated original by Daron Spence.
  * Author: LewisCowles
- * Version: 1.0.6
+ * Version: 1.0.7
  */
 
 add_action( 'wp_footer', function(){
@@ -52,9 +52,12 @@
 						container.parentNode.insertBefore(buttons.cloneNode(true), container.nextSibling);
 
 						mediaTag.addEventListener('loadedmetadata', function(e) {
-							var activeSpeed = e.target.closest('.wp-playlist').querySelector('.mejs-container .playback-rate-button.mejs-active');
-								rate = activeSpeed.dataset.value;
-							e.target.setPlaybackRate(rate);
+							var playlist = e.target.closest('.wp-playlist');
+							if(playlist) {
+								var activeSpeed = playlist.querySelector('.mejs-container .playback-rate-button.mejs-active'),
+									rate = activeSpeed.dataset.value;
+								e.target.setPlaybackRate(rate);
+							}
 						});
 					}
 				});

readme.txt

@@ -4,7 +4,7 @@ Tags: frontend,media,streaming,aria,mediaelementjs,html5,video,audio,playback,sp
 Requires at least: 4.0
 Tested up to: 5.2.2
 Requires PHP: 5.6
-Stable tag: 1.0.6
+Stable tag: 1.0.7
 License: GPL-3.0
 License URI: https://www.gnu.org/licenses/gpl-3.0.html
 
@@ -37,6 +37,9 @@ Please feel free to [suggest](https://github.com/CODESIGN2/media-playback-speed/
 Download and extract the zip file or clone this repo to your WordPress plugins directory. Alternatively use the plugin directory to find and install this plugin.
 
 == Changelog ==
+= 1.0.7 =
+* guard to prevent errors
+
 = 1.0.6 =
 * change of DOM event