[gnome-builder] flatpak: ensure that arch is not (null)

[Christian Hergert <chergert src gnome org>]

commit 4d24ee26fd5cc71fe3d3c19fc8711bf14a1c0e04
Author: Christian Hergert <chergert redhat com>
Date:   Fri Apr 30 13:54:34 2021 -0700

    flatpak: ensure that arch is not (null)

 src/plugins/flatpak/gbp-flatpak-install-dialog.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
---
diff --git a/src/plugins/flatpak/gbp-flatpak-install-dialog.c 
b/src/plugins/flatpak/gbp-flatpak-install-dialog.c
index 186043e4e..939e37b26 100644
--- a/src/plugins/flatpak/gbp-flatpak-install-dialog.c
+++ b/src/plugins/flatpak/gbp-flatpak-install-dialog.c
@@ -79,7 +79,13 @@ get_runtimes (GbpFlatpakInstallDialog *self)
                               2, &branch,
                               -1);
 
-          g_ptr_array_add (ar, g_strdup_printf ("%s/%s/%s", name, arch, branch ?: ""));
+          if (arch == NULL)
+            arch = g_strdup (flatpak_get_default_arch ());
+
+          if (branch == NULL)
+            branch = g_strdup ("");
+
+          g_ptr_array_add (ar, g_strdup_printf ("%s/%s/%s", name, arch, branch));
         }
       while (gtk_tree_model_iter_next (GTK_TREE_MODEL (self->liststore1), &iter));
     }