[rygel] renderer: Prevent critical on null mime-type

[Jens Georg <jensgeorg src gnome org>]

commit dc1db158c15015f14a53e71e8b8c9db87e925991
Author: Jens Georg <mail jensge org>
Date:   Tue Feb 12 00:28:15 2019 +0100

    renderer: Prevent critical on null mime-type

 src/librygel-renderer/rygel-default-player-controller.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/librygel-renderer/rygel-default-player-controller.vala 
b/src/librygel-renderer/rygel-default-player-controller.vala
index 7e0c8ef9..40ad0fc1 100644
--- a/src/librygel-renderer/rygel-default-player-controller.vala
+++ b/src/librygel-renderer/rygel-default-player-controller.vala
@@ -172,7 +172,7 @@ internal class Rygel.DefaultPlayerController : Rygel.PlayerController, Object {
                 actions += ",X_DLNA_SeekByte";
             }
 
-            if (!this.player.mime_type.has_prefix ("image/") &&
+            if (this.player.mime_type != null && !this.player.mime_type.has_prefix ("image/") &&
                 this.player.allowed_playback_speeds.length > 1) {
                 string play_speeds = "";
                 foreach (var speed in this.player.allowed_playback_speeds) {