fix: Don't throw an error when trying to disable a trick mode stream (#…

…7235)

lib/player.js

@@ -7260,19 +7260,32 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
     if (hasAltStream) {
       let didDisableStream = false;
 
+      let isTrickModeVideo = false;
+
       for (const variant of this.manifest_.variants) {
         const candidate = variant[stream.type];
 
-        if (candidate && candidate.id === stream.id) {
+        if (!candidate) {
+          continue;
+        }
+
+        if (candidate.id === stream.id) {
           variant.disabledUntilTime = (Date.now() / 1000) + disableTime;
           didDisableStream = true;
 
           shaka.log.v2(
               'Disabled stream ' + stream.type + ':' + stream.id +
               ' for ' + disableTime + ' seconds...');
+        } else if (candidate.trickModeVideo &&
+            candidate.trickModeVideo.id == stream.id) {
+          isTrickModeVideo = true;
         }
       }
 
+      if (!didDisableStream && isTrickModeVideo) {
+        return false;
+      }
+
       goog.asserts.assert(didDisableStream, 'Must have disabled stream');
 
       this.checkVariantsTimer_.tickEvery(1);