[gnome-boxes/icon-view-context-popover-unset-child] icon-view: Don't launch context popover if icon-view item is unset

[Felipe Borges <felipeborges src gnome org>]

commit 0450044199a080f5b4a4071220d1282f48a9b161
Author: Felipe Borges <felipeborges gnome org>
Date:   Tue Sep 13 11:32:05 2022 +0200

    icon-view: Don't launch context popover if icon-view item is unset

 src/icon-view.vala | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/src/icon-view.vala b/src/icon-view.vala
index f20b25ea..b3026b19 100644
--- a/src/icon-view.vala
+++ b/src/icon-view.vala
@@ -58,6 +58,8 @@ private bool on_button_press_event (Gdk.EventButton event) {
             return false;
 
         var child = flowbox.get_child_at_pos ((int) event.x, (int) event.y);
+        if (child == null)
+            return false;
 
         return launch_context_popover_for_child (child);
     }