[gnome-builder] ide-source-view: fix progress bar critical's error

[Sébastien Lafargue <slafargue src gnome org>]

commit d406f9d007791059550d9b4b4b3d1fd0d6e4e3ea
Author: Sebastien Lafargue <slafargue gnome org>
Date:   Tue Feb 2 19:34:31 2016 +0100

    ide-source-view: fix progress bar critical's error
    
    When closing an editor view with command bar 'quit' command,
    we get:
    
    ide-gtk[17188]:
     CRITICAL: ide_widget_hide_with_fade:
     assertion 'GTK_IS_WIDGET (widget)' failed

 libide/editor/ide-editor-view-actions.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/libide/editor/ide-editor-view-actions.c b/libide/editor/ide-editor-view-actions.c
index 9ca58bc..becfac8 100644
--- a/libide/editor/ide-editor-view-actions.c
+++ b/libide/editor/ide-editor-view-actions.c
@@ -189,7 +189,8 @@ save_file_cb (GObject      *object,
       g_clear_error (&error);
     }
 
-  ide_widget_hide_with_fade (GTK_WIDGET (self->progress_bar));
+  if (self->progress_bar)
+    ide_widget_hide_with_fade (GTK_WIDGET (self->progress_bar));
 }
 
 static void