[rhythmbox] shell-player: return error information from rb_shell_player_play on failure

[Jonathan Matthew <jmatthew src gnome org>]

commit 2bf5d32d22594e6e34a0e50c7e60958303d51744
Author: Jonathan Matthew <jonathan d14n org>
Date:   Sun Aug 29 22:32:23 2010 +1000

    shell-player: return error information from rb_shell_player_play on failure

 shell/rb-shell-player.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/shell/rb-shell-player.c b/shell/rb-shell-player.c
index e5b32ee..faba668 100644
--- a/shell/rb-shell-player.c
+++ b/shell/rb-shell-player.c
@@ -1641,6 +1641,10 @@ rb_shell_player_play (RBShellPlayer *player,
 
 	if (player->priv->current_playing_source == NULL) {
 		rb_debug ("current playing source is NULL");
+		g_set_error (error,
+			     RB_SHELL_PLAYER_ERROR,
+			     RB_SHELL_PLAYER_ERROR_NOT_PLAYING,
+			     "Current playing source is NULL");
 		return FALSE;
 	}