lib: Fix notmuch_query_search_threads to return NULL on any Xapian exception.

Previously, if the underlying search_messages hit an exception and returned
NULL, this function would ignore that and return a non-NULL, (but empty)
threads object. Fix this to properly propagate the error.

1 files changed, 2 insertions, 0 deletions

diff --git a/lib/notmuch.h b/lib/notmuch.h
index 505ad19f..9a196999 100644
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -400,6 +400,8 @@ notmuch_query_set_sort (notmuch_query_t *query, notmuch_sort_t sort);
  * notmuch_threads_t object. (For consistency, we do provide a
  * notmuch_threads_destroy function, but there's no good reason
  * to call it if the query is about to be destroyed).
+ *
+ * If a Xapian exception occurs this function will return NULL.
  */
 notmuch_threads_t *
 notmuch_query_search_threads (notmuch_query_t *query);