fix some undefined bugs

dist/videojs-contrib-hls.js

@@ -5474,7 +5474,7 @@ var SegmentLoader = (function (_videojs$EventTarget) {
       // Wait at least 1 second since the first byte of data has been received before
       // using the calculated bandwidth from the progress event to allow the bitrate
       // to stabilize
-      if (Date.now() - stats.firstByteRoundTripTime < 1000) {
+      if (Date.now() - (stats.firstByteRoundTripTime || Date.now()) < 1000) {
         return false;
       }
 
@@ -6383,7 +6383,7 @@ var syncPointStrategies = [
 {
   name: 'Segment',
   run: function run(syncController, playlist, duration, currentTimeline, currentTime) {
-    var segments = playlist.segments;
+    var segments = playlist.segments || [];
     var syncPoint = null;
     var lastDistance = null;
 
@@ -6422,7 +6422,7 @@ var syncPointStrategies = [
 
     currentTime = currentTime || 0;
 
-    if (playlist.discontinuityStarts.length) {
+    if (playlist.discontinuityStarts && playlist.discontinuityStarts.length) {
       var lastDistance = null;
 
       for (var i = 0; i < playlist.discontinuityStarts.length; i++) {

src/segment-loader.js

@@ -736,7 +736,7 @@ export default class SegmentLoader extends videojs.EventTarget {
     // Wait at least 1 second since the first byte of data has been received before
     // using the calculated bandwidth from the progress event to allow the bitrate
     // to stabilize
-    if (Date.now() - stats.firstByteRoundTripTime < 1000) {
+    if (Date.now() - (stats.firstByteRoundTripTime || Date.now()) < 1000) {
       return false;
     }
 

src/sync-controller.js

@@ -46,7 +46,7 @@ export const syncPointStrategies = [
   {
     name: 'Segment',
     run: (syncController, playlist, duration, currentTimeline, currentTime) => {
-      let segments = playlist.segments;
+      let segments = playlist.segments || [];
       let syncPoint = null;
       let lastDistance = null;
 
@@ -87,7 +87,7 @@ export const syncPointStrategies = [
 
       currentTime = currentTime || 0;
 
-      if (playlist.discontinuityStarts.length) {
+      if (playlist.discontinuityStarts && playlist.discontinuityStarts.length) {
         let lastDistance = null;
 
         for (let i = 0; i < playlist.discontinuityStarts.length; i++) {