adress review comments

externs/shaka/player.js

@@ -1081,9 +1081,9 @@ shaka.extern.ManifestConfiguration;
  * @property {boolean} segmentPrefetchLimit
  *   The maximum number of segments for each active stream to be prefetched
  *   ahead of playhead in parallel.
- *   If <code>null</code> or <code><1</code>, the segments will be fetched
+ *   If <code>0</code>, the segments will be fetched
  *   sequentially.
- *   Defaults to <code>null</code>.
+ *   Defaults to <code>0</code>.
  * @exportDoc
  */
 shaka.extern.StreamingConfiguration;

lib/media/streaming_engine.js

@@ -178,10 +178,8 @@ shaka.media.StreamingEngine = class {
       if (state.segmentPrefetch) {
         state.segmentPrefetch.resetLimit(config.segmentPrefetchLimit);
         if (!(config.segmentPrefetchLimit > 0)) {
-          /**
-           * ResetLimit is still needed in this case,
-           * to abort existing prefetch operations.
-           */
+          // ResetLimit is still needed in this case,
+          // to abort existing prefetch operations.
           state.segmentPrefetch = null;
         }
       } else if (config.segmentPrefetchLimit > 0) {
@@ -1142,6 +1140,7 @@ shaka.media.StreamingEngine = class {
     return null;
   }
 
+
   /**
    * Gets the next timestamp needed. Returns the playhead's position if the
    * buffer is empty; otherwise, returns the time at which the last segment
@@ -2071,7 +2070,6 @@ shaka.media.StreamingEngine = class {
    *
    * @return {!shaka.net.NetworkingEngine.PendingRequest}
    * @private
-   * @suppress {strictMissingProperties}
    */
   dispatchFetch_(reference, stream, streamDataCallback) {
     const requestType = shaka.net.NetworkingEngine.RequestType.SEGMENT;
@@ -2084,13 +2082,17 @@ shaka.media.StreamingEngine = class {
         streamDataCallback);
 
     shaka.log.v2('fetching: reference=', reference);
-
+    let duration = 0;
+    if ((reference instanceof shaka.media.SegmentReference)) {
+      // start and endTime are not defined in InitSegmentReference
+      duration = reference.endTime - reference.startTime;
+    }
     this.playerInterface_.modifySegmentRequest(
         request,
         {
           type: stream.type,
           init: reference instanceof shaka.media.InitSegmentReference,
-          duration: reference.endTime - reference.startTime,
+          duration: duration,
           mimeType: stream.mimeType,
           codecs: stream.codecs,
           bandwidth: stream.bandwidth,