[gnome-builder] ctags: Do not try to enumerate a NULL numerator

[Christian Hergert <chergert src gnome org>]

commit d80f77db888d682a8cab6d1be5ed299985067e7a
Author: Thibault Saunier <tsaunier gnome org>
Date:   Fri Dec 18 10:37:22 2015 +0100

    ctags: Do not try to enumerate a NULL numerator
    
    https://bugzilla.gnome.org/show_bug.cgi?id=759621

 plugins/ctags/ide-ctags-service.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/plugins/ctags/ide-ctags-service.c b/plugins/ctags/ide-ctags-service.c
index 0aaa1de..775549e 100644
--- a/plugins/ctags/ide-ctags-service.c
+++ b/plugins/ctags/ide-ctags-service.c
@@ -291,6 +291,9 @@ ide_ctags_service_mine_directory (IdeCtagsService *self,
                                           cancellable,
                                           NULL);
 
+  if (!enumerator)
+    return;
+
   while ((infoptr = g_file_enumerator_next_file (enumerator, cancellable, NULL)))
     {
       g_autoptr(GFileInfo) file_info = infoptr;