check if captions exists

src/js/plyr.js

@@ -1517,6 +1517,7 @@
         function setCaption(caption) {
             var captions = getElement(config.selectors.captions);
             var content = document.createElement('span');
+            if(captions) {
 
               // Empty the container
               captions.innerHTML = '';
@@ -1540,6 +1541,8 @@
               var redraw = captions.offsetHeight;
             }
 
+        }
+
         // Captions functions
         // Seek the manual caption time and update UI
         function seekManualCaptions(time) {