Check if local subtitle file exists before loading it

Otherwise GStreamer will error out and playback will stop. Non-existing subtitle file is common on Flatpak when user tries to open/drop a file from a folder that container does not have access to.

src/misc.js

@@ -126,6 +126,19 @@ function parsePlaylistFiles(filesArray)
     return [filesArray, subs];
 }
 
+function getFileFromLocalUri(uri)
+{
+    const file = Gio.file_new_for_uri(uri);
+
+    if(!file.query_exists(null)) {
+        debug(`file does not exist: ${file.get_path()}`, 'LEVEL_WARNING');
+
+        return null;
+    }
+
+    return file;
+}
+
 function encodeHTML(text)
 {
     return text.replace(/&/g, '&')

src/player.js

@@ -60,10 +60,8 @@ class ClapperPlayer extends PlayerBase
             return;
         }
 
-        let file = Gio.file_new_for_uri(uri);
+        const file = Misc.getFileFromLocalUri(uri);
-        if(!file.query_exists(null)) {
+        if(!file) {
-            debug(`file does not exist: ${file.get_path()}`, 'LEVEL_WARNING');
-
             if(!this.playlistWidget.nextTrack())
                 debug('set media reached end of playlist');
 
@@ -160,6 +158,13 @@ class ClapperPlayer extends PlayerBase
     {
         const uri = this._getSourceUri(source);
 
+        /* Check local file existence */
+        if(
+            Gst.Uri.get_protocol(uri) === 'file'
+            && !Misc.getFileFromLocalUri(uri)
+        )
+            return;
+
         this.set_subtitle_uri(uri);
         this.set_subtitle_track_enabled(true);