[glom] Dialog_Line: Avoid a possible null dereference.

[Murray Cumming <murrayc src gnome org>]

commit 4b4ee39472fcfcef71563070fda3bacbfff451bb
Author: Murray Cumming <murrayc murrayc com>
Date:   Tue Mar 29 18:19:20 2016 +0200

    Dialog_Line: Avoid a possible null dereference.

 .../layout/layout_item_dialogs/dialog_line.cc      |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/glom/mode_design/layout/layout_item_dialogs/dialog_line.cc 
b/glom/mode_design/layout/layout_item_dialogs/dialog_line.cc
index 4392295..09e720f 100644
--- a/glom/mode_design/layout/layout_item_dialogs/dialog_line.cc
+++ b/glom/mode_design/layout/layout_item_dialogs/dialog_line.cc
@@ -51,6 +51,7 @@ void Dialog_Line::set_line(const std::shared_ptr<const LayoutItem_Line>& line)
   if(!line)
   {
     std::cerr << G_STRFUNC << ": line is null\n";
+    return;
   }
 
   //set_blocked();