[nautilus] canvas-container: account for keyboard event == NULL

[Cosimo Cecchi <cosimoc src gnome org>]

commit 8d230eb54a589feb8b91d71828cbac9ba80cd8a6
Author: Cosimo Cecchi <cosimoc gnome org>
Date:   Sat Jul 6 14:29:46 2019 -0700

    canvas-container: account for keyboard event == NULL
    
    Every other code path accounts for it; we'll rely on this code
    being NULL-safe in a following commit, so make this function also
    deal with it gracefully.

 src/nautilus-canvas-container.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/src/nautilus-canvas-container.c b/src/nautilus-canvas-container.c
index 272d1e37c..994f519a4 100644
--- a/src/nautilus-canvas-container.c
+++ b/src/nautilus-canvas-container.c
@@ -2760,7 +2760,8 @@ keyboard_arrow_key (NautilusCanvasContainer *container,
 static gboolean
 is_rectangle_selection_event (GdkEventKey *event)
 {
-    return (event->state & GDK_CONTROL_MASK) != 0 &&
+    return event != NULL &&
+           (event->state & GDK_CONTROL_MASK) != 0 &&
            (event->state & GDK_SHIFT_MASK) != 0;
 }