Fallback to empty fonts list when server doesn't send MediaAttachments.

src/components/htmlvideoplayer/plugin.js

@@ -1038,10 +1038,11 @@ define(['browser', 'require', 'events', 'apphost', 'loading', 'dom', 'playbackMa
         }
 
         function renderWithSubtitlesOctopus(videoElement, track, item) {
+            var attachments = self._currentPlayOptions.mediaSource.MediaAttachments || [];
             var options = {
                 video: videoElement,
                 subUrl: getTextTrackUrl(track, item),
-                fonts: self._currentPlayOptions.mediaSource.MediaAttachments.map(i => i.DeliveryUrl),
+                fonts: attachments.map(i => i.DeliveryUrl),
                 workerUrl: appRouter.baseUrl() + "/node_modules/libass-wasm/dist/subtitles-octopus-worker.js",
                 onError: function() {
                     htmlMediaHelper.onErrorInternal(self, 'mediadecodeerror')

yarn.lock

@@ -2510,6 +2510,11 @@ levn@^0.3.0, levn@~0.3.0:
     prelude-ls "~1.1.2"
     type-check "~0.3.2"
 
+libass-wasm@^2.1.1:
+  version "2.1.1"
+  resolved "https://registry.yarnpkg.com/libass-wasm/-/libass-wasm-2.1.1.tgz#f12f4fdb9579dd422dcbc348bc3bd61097f4d07d"
+  integrity sha512-d45bHQ7tFVsLW3QstQDrDog2m+0D6Cja4GTrkGi70R9A5+aeLunPSUz3G4CVB+sKffNgiWjK4QI5NZLHQKZ9oQ==
+
 libjass@^0.11.0:
   version "0.11.0"
   resolved "https://registry.yarnpkg.com/libjass/-/libjass-0.11.0.tgz#bff1f464a2428c3bddfb68e4503b2d52afe3d6e6"