player/Control: Seek*() returns Error information

src/player/Control.cxx

@@ -204,8 +204,8 @@ PlayerControl::LockEnqueueSong(DetachedSong *song)
 	EnqueueSongLocked(song);
 }
 
-void
-PlayerControl::SeekLocked(DetachedSong *song, SongTime t)
+bool
+PlayerControl::SeekLocked(DetachedSong *song, SongTime t, Error &error_r)
 {
 	assert(song != nullptr);
 
@@ -214,21 +214,32 @@ PlayerControl::SeekLocked(DetachedSong *song, SongTime t)
 
 	assert(next_song == nullptr);
 
+	ClearError();
 	next_song = song;
 	seek_time = t;
 	SynchronousCommand(PlayerCommand::SEEK);
 
 	assert(next_song == nullptr);
+
+	if (error_type != PlayerError::NONE) {
+		assert(error.IsDefined());
+		error_r.Set(error);
+		return false;
+	}
+
+	assert(!error.IsDefined());
+	return true;
 }
 
 bool
-PlayerControl::LockSeek(DetachedSong *song, SongTime t)
+PlayerControl::LockSeek(DetachedSong *song, SongTime t, Error &error_r)
 {
 	assert(song != nullptr);
 
 	{
 		const ScopeLock protect(mutex);
-		SeekLocked(song, t);
+		if (!SeekLocked(song, t, error_r))
+			return false;
 	}
 
 	idle_add(IDLE_PLAYER);

src/player/Control.hxx

@@ -425,7 +425,7 @@ private:
 		SynchronousCommand(PlayerCommand::QUEUE);
 	}
 
-	void SeekLocked(DetachedSong *song, SongTime t);
+	bool SeekLocked(DetachedSong *song, SongTime t, Error &error_r);
 
 public:
 	/**
@@ -442,7 +442,7 @@ public:
 	 * @return true on success, false on failure (e.g. if MPD isn't
 	 * playing currently)
 	 */
-	bool LockSeek(DetachedSong *song, SongTime t);
+	bool LockSeek(DetachedSong *song, SongTime t, Error &error_r);
 
 	void SetCrossFade(float cross_fade_seconds);
 

src/queue/PlaylistControl.cxx

@@ -211,12 +211,8 @@ playlist::SeekSongOrder(PlayerControl &pc, unsigned i, SongTime seek_time,
 		queued_song = nullptr;
 	}
 
-	if (!pc.LockSeek(new DetachedSong(queue.GetOrder(i)), seek_time)) {
+	if (!pc.LockSeek(new DetachedSong(queue.GetOrder(i)), seek_time, error)) {
 		UpdateQueuedSong(pc, queued_song);
-
-		// TODO: fix error code
-		error.Set(playlist_domain, int(PlaylistResult::NOT_PLAYING),
-			  "Decoder failed to seek");
 		return false;
 	}