lib: catch error from closed db in n_m_get_message_id

By catching it at the library top level, we can return an error value.

1 files changed, 2 insertions, 3 deletions

diff --git a/lib/notmuch.h b/lib/notmuch.h
index ceb5a018..0dc89547 100644
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -1363,9 +1363,8 @@ notmuch_message_get_database (const notmuch_message_t *message);
  * message is valid, (which is until the query from which it derived
  * is destroyed).
  *
- * This function will not return NULL since Notmuch ensures that every
- * message has a unique message ID, (Notmuch will generate an ID for a
- * message if the original file does not contain one).
+ * This function will return NULL if triggers an unhandled Xapian
+ * exception.
  */
 const char *
 notmuch_message_get_message_id (notmuch_message_t *message);