[gnome-games] utils: Check null values

[Adrien Plazas <aplazas src gnome org>]

commit 0aee4701f4564aba41fe9a5852da9ddc9a06264a
Author: Mathieu Bridon <bochecha daitauha fr>
Date:   Thu Apr 27 23:25:14 2017 +0200

    utils: Check null values
    
    These two functions can return null in some cases. Passing null to the
    FileUtils.test function leads to lots of critical messages in the
    console.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=781864

 src/utils/local-cover.vala |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/utils/local-cover.vala b/src/utils/local-cover.vala
index daf6f6c..4ad02a9 100644
--- a/src/utils/local-cover.vala
+++ b/src/utils/local-cover.vala
@@ -36,11 +36,11 @@ public class Games.LocalCover : Object, Cover {
 
        private string? get_cover_path () throws Error {
                var cover_path = get_sibbling_cover_path ();
-               if (FileUtils.test (cover_path, FileTest.EXISTS))
+               if (cover_path != null && FileUtils.test (cover_path, FileTest.EXISTS))
                        return cover_path;
 
                cover_path = get_directory_cover_path ();
-               if (FileUtils.test (cover_path, FileTest.EXISTS))
+               if (cover_path != null && FileUtils.test (cover_path, FileTest.EXISTS))
                        return cover_path;
 
                return null;