Fix sx-tag-filter

It wasn't returning any .items because it wasn't included in the
filter.  This commit also introduces a convenience macro in sx-filter to
avoid this scenario in the future.

1 files changed, 3 insertions, 1 deletions

diff --git a/sx-tag.el b/sx-tag.el
index 511c474..9f8a5a9 100644
--- a/sx-tag.el
+++ b/sx-tag.el
@@ -26,7 +26,9 @@
 
 
 ;;; Getting the list from a site
-(defvar sx-tag-filter '((tag.name))
+(defvar sx-tag-filter
+  (sx-filter-from-nil
+   (tag.name))
   "Filter used when querying tags.")
 
 (defun sx-tag--get-some-tags-containing (site string)