[gnome-boxes] wizard: Turn a check into return_val_if_fail

[Zeeshan Ali Khattak <zeeshanak src gnome org>]

commit 4533c16195eceae27317ca1fe852526c0db0a328
Author: Zeeshan Ali (Khattak) <zeeshanak gnome org>
Date:   Wed Jul 4 21:51:34 2012 +0300

    wizard: Turn a check into return_val_if_fail
    
    https://bugzilla.gnome.org/show_bug.cgi?id=678902

 src/wizard.vala |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)
---
diff --git a/src/wizard.vala b/src/wizard.vala
index 0a7060d..167e6b5 100644
--- a/src/wizard.vala
+++ b/src/wizard.vala
@@ -178,8 +178,7 @@ private class Boxes.Wizard: Boxes.UI {
 
     private bool create () {
         if (source == null) {
-            if (vm_creator == null)
-                return false;
+            return_val_if_fail (vm_creator != null, false); // Shouldn't arrive here with source & vm_creator being null
 
             next_button.sensitive = false;
             try {