Invert conditional to remove a level of indentation

The segment response callback was getting pretty deeply nested, so invert the readyState check and return early. Also added some comments.

@@ -292,11 +292,10 @@ var
           // always start playback with the default rendition
           if (!player.hls.media) {
             player.hls.media = player.hls.master.playlists[0];
-            if (parser.manifest.totalDuration) {
+
             // update the duration
+            if (parser.manifest.totalDuration) {
               player.duration(parser.manifest.totalDuration);
-              // Notify the flash layer
-              //player.el().querySelector('.vjs-tech').vjs_setProperty('duration',parser.manifest.totalDuration);
             } else {
               player.duration(totalDuration(parser.manifest));
             }
@@ -311,8 +310,9 @@ var
             downloadPlaylist(resolveUrl(srcUrl, playlist.uri));
           } else {
             player.hls.media = playlist;
-            if (player.hls.media.totalDuration) {
+
             // update the duration
+            if (player.hls.media.totalDuration) {
               player.duration(player.hls.media.totalDuration);
             } else {
               player.duration(totalDuration(player.hls.media));
@@ -370,14 +370,8 @@ var
       segmentXhr.onreadystatechange = function() {
         var playlist;
 
-       if (this.readyState === 4) {
-         if (this.status >= 400) {
-           player.hls.error = {
-             status: segmentXhr.status,
-             message: 'HLS segment request error at URL: ' + segmentUri,
-             code: (segmentXhr.status >= 500) ? 4 : 2
-           };
-           player.trigger('error');
+        // wait until the request completes
+        if (this.readyState !== 4) {
           return;
         }
 
@@ -389,6 +383,17 @@ var
           return;
         }
 
+        // trigger an error if the request was not successful
+        if (this.status >= 400) {
+          player.hls.error = {
+            status: segmentXhr.status,
+            message: 'HLS segment request error at URL: ' + segmentUri,
+            code: (segmentXhr.status >= 500) ? 4 : 2
+          };
+          player.trigger('error');
+          return;
+        }
+
         // calculate the download bandwidth
         player.hls.segmentXhrTime = (+new Date()) - startTime;
         player.hls.bandwidth = (this.response.byteLength / player.hls.segmentXhrTime) * 8 * 1000;
@@ -415,7 +420,6 @@ var
         player.hls.mediaIndex++;
 
         if (player.hls.mediaIndex === player.hls.media.segments.length) {
-            //TODO - Fix the endofstream //
           mediaSource.endOfStream();
           return;
         }
@@ -428,7 +432,6 @@ var
         } else {
           player.hls.media = playlist;
         }
-        }
       };
       startTime = +new Date();
       segmentXhr.send(null);