[gnome-boxes] wizard: Check for null results in media lists

[Felipe Borges <felipeborges src gnome org>]

commit 61c9ae768a838fa24c9a2583691c57f1ed493c5d
Author: Diego Escalante Urrelo <diegoe gnome org>
Date:   Mon Nov 4 14:21:46 2019 -0500

    wizard: Check for null results in media lists
    
    Make sure that media results are not null before trying to use them as
    GObjects. This prevents a bunch of crashes related to the wizard and
    application startup.
    
    See: https://gitlab.com/libosinfo/libosinfo/merge_requests/23
    Fixes: https://gitlab.gnome.org/GNOME/gnome-boxes/issues/433

 src/search.vala                | 6 ++++--
 src/wizard-downloads-page.vala | 4 +++-
 src/wizard-source.vala         | 4 +++-
 3 files changed, 10 insertions(+), 4 deletions(-)
---
diff --git a/src/search.vala b/src/search.vala
index 09ef2889..46970fbc 100644
--- a/src/search.vala
+++ b/src/search.vala
@@ -50,14 +50,16 @@
 
     private async void load_custom_downloads () {
         foreach (var media in yield get_recommended_downloads ()) {
-            if (media.url == null)
+            if (media != null && media.url == null)
                 media_list.append (media);
         }
     }
 
     public void show_all () {
         foreach (var media in media_list) {
-            model.append (media);
+            if (media != null) {
+                model.append (media);
+            }
         }
     }
 }
diff --git a/src/wizard-downloads-page.vala b/src/wizard-downloads-page.vala
index 0b77a9cb..e001381f 100644
--- a/src/wizard-downloads-page.vala
+++ b/src/wizard-downloads-page.vala
@@ -69,7 +69,9 @@ private void set_visible_view () {
 
     private async void populate_recommended_list () {
         foreach (var media in yield get_recommended_downloads ()) {
-            recommended_model.append (media);
+            if (media != null) {
+                recommended_model.append (media);
+            }
         }
     }
 
diff --git a/src/wizard-source.vala b/src/wizard-source.vala
index a470d1f3..d008692f 100644
--- a/src/wizard-source.vala
+++ b/src/wizard-source.vala
@@ -394,7 +394,9 @@ public void setup_ui (AppWindow window) {
 
     private async void populate_recommended_downloads () {
         foreach (var media in yield get_recommended_downloads ()) {
-            downloads_model.append (media);
+            if (media != null) {
+                downloads_model.append (media);
+            }
         }
     }