[gnome-boxes] Add NULL checks for InstallerMedia.os_media

[Zeeshan Ali Khattak <zeeshanak src gnome org>]

commit 4262510a5f624a6d9c492792bb7f07c762312e9d
Author: Zeeshan Ali (Khattak) <zeeshanak gnome org>
Date:   Mon Dec 2 23:37:49 2013 +0000

    Add NULL checks for InstallerMedia.os_media
    
    Check if InstallerMedia.os_media is non-null before using it, otherwise
    we get a crash if its NULL.

 src/installer-media.vala |    2 +-
 src/vm-creator.vala      |   10 ++++++----
 2 files changed, 7 insertions(+), 5 deletions(-)
---
diff --git a/src/installer-media.vala b/src/installer-media.vala
index 9bc42bc..af3b205 100644
--- a/src/installer-media.vala
+++ b/src/installer-media.vala
@@ -148,7 +148,7 @@ private class Boxes.InstallerMedia : GLib.Object {
     protected void label_setup (string? label = null) {
         if (label != null)
             this.label = label;
-        else if (os != null) {
+        else if (os != null && os_media != null) {
             var variants = os_media.get_os_variants ();
             if (variants.get_length () > 0)
                 // FIXME: Assuming first variant only from multivariant medias.
diff --git a/src/vm-creator.vala b/src/vm-creator.vala
index 2005723..dbd5dbc 100644
--- a/src/vm-creator.vala
+++ b/src/vm-creator.vala
@@ -227,10 +227,12 @@ private class Boxes.VMCreator {
         if (install_media.os != null) {
             base_name = install_media.os.short_id;
 
-            var variants = install_media.os_media.get_os_variants ();
-            if (variants.get_length () > 0)
-                // FIXME: Assuming first variant only from multivariant medias.
-                base_name += "-" + variants.get_nth (0).id;
+            if (install_media.os_media != null) {
+                var variants = install_media.os_media.get_os_variants ();
+                if (variants.get_length () > 0)
+                    // FIXME: Assuming first variant only from multivariant medias.
+                    base_name += "-" + variants.get_nth (0).id;
+            }
         } else
             base_name = "boxes-unknown";
     }