Guards against missing VideoJS plugins/elements

Adds checks to ensure VideoJS plugins and control elements
exist before attempting to initialize or modify them. This
prevents errors when certain plugins or elements are not
available or have not yet been initialized, improving
robustness. Also includes logic to dispose and remove a
previously initialized player to resolve conflicts during
initialization.

Author: tzarebczan

ui/component/viewers/videoViewer/internal/plugins/videojs-mobile-ui/plugin.js

@@ -66,8 +66,19 @@ const onPlayerReady = (player, options) => {
 
   const controlBar = player.getChild('ControlBar');
 
-  // Insert before the ControlBar:
+  // Guard: ControlBar must exist and be in the player's children
+  if (!controlBar) {
+    videojs.log.warn('mobileUi: ControlBar not found, skipping mobile UI setup');
+    return;
+  }
+
   const controlBarIdx = player.children_.indexOf(controlBar);
+  if (controlBarIdx === -1) {
+    videojs.log.warn('mobileUi: ControlBar not in player children, skipping mobile UI setup');
+    return;
+  }
+
+  // Insert before the ControlBar:
   player.addChild('touchOverlay', options.touchControls, controlBarIdx);
 
   // Make the TouchOverlay the new parent of the ControlBar.

ui/component/viewers/videoViewer/internal/videojs.jsx

@@ -327,24 +327,30 @@ export default React.memo<Props>(function VideoJs(props: Props) {
 
       player.appState = {};
 
-      player.reloadSourceOnError({ errorInterval: 10 });
-
-      player.mobileUi({
-        fullscreen: {
-          enterOnRotate: false,
-        },
-        touchControls: {
-          seekSeconds: 10,
-        },
-      });
-
-      player.i18n();
-      player.settingsMenu();
-      player.timeMarkerPlugin();
-      player.hlsQualitySelector({ displayCurrentQuality: true });
+      if (typeof player.reloadSourceOnError === 'function') {
+        player.reloadSourceOnError({ errorInterval: 10 });
+      }
+
+      if (typeof player.mobileUi === 'function') {
+        player.mobileUi({
+          fullscreen: {
+            enterOnRotate: false,
+          },
+          touchControls: {
+            seekSeconds: 10,
+          },
+        });
+      }
+
+      if (typeof player.i18n === 'function') player.i18n();
+      if (typeof player.settingsMenu === 'function') player.settingsMenu();
+      if (typeof player.timeMarkerPlugin === 'function') player.timeMarkerPlugin();
+      if (typeof player.hlsQualitySelector === 'function') {
+        player.hlsQualitySelector({ displayCurrentQuality: true });
+      }
 
       // Add recsys plugin
-      if (shareTelemetry) {
+      if (shareTelemetry && typeof player.recsys === 'function') {
         player.recsys({
           videoId: claimId,
           userId: userId,
@@ -359,13 +365,15 @@ export default React.memo<Props>(function VideoJs(props: Props) {
 
       Chromecast.initialize(player);
 
-      player.airPlay();
+      if (typeof player.airPlay === 'function') player.airPlay();
 
-      player.watchdog({
-        timeoutMs: 15000,
-        livestreamsOnly: true,
-        action: () => setReload(Date.now()),
-      });
+      if (typeof player.watchdog === 'function') {
+        player.watchdog({
+          timeoutMs: 15000,
+          livestreamsOnly: true,
+          action: () => setReload(Date.now()),
+        });
+      }
     });
 
     // fixes #3498 (https://github.com/lbryio/lbry-desktop/issues/3498)
@@ -403,6 +411,17 @@ export default React.memo<Props>(function VideoJs(props: Props) {
 
       // initialize videojs if it hasn't been done yet
       if (!canUseOldPlayer) {
+        // Dispose old player if it exists to prevent "already initialised" conflicts
+        if (window.player && typeof window.player.dispose === 'function') {
+          try {
+            window.player.dispose();
+          } catch (e) {
+            console.warn('Failed to dispose old player:', e);
+          }
+          window.player = null;
+          window.oldSavedDiv = null;
+        }
+
         const vjsElement = createVideoPlayerDOM(containerRef.current);
         vjsPlayer = initializeVideoPlayer(vjsElement);
         if (!vjsPlayer) {