From 84b8b32866f7270f88b71a2104dd27fcb3d028c0 Mon Sep 17 00:00:00 2001
From: Charles Haley <github@charles.haleys.org>
Date: Sun, 18 Sep 2016 10:43:51 +0200
Subject: [PATCH] When in debug mode, print the lookup name of the column with
 a template that is throwing an exception.

---
 src/calibre/utils/formatter.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/calibre/utils/formatter.py b/src/calibre/utils/formatter.py
index 7fa4b1b080..075c34dfa5 100644
--- a/src/calibre/utils/formatter.py
+++ b/src/calibre/utils/formatter.py
@@ -525,6 +525,8 @@ class TemplateFormatter(string.Formatter):
         except Exception as e:
             if DEBUG:  # and getattr(e, 'is_locking_error', False):
                 traceback.print_exc()
+                if column_name:
+                    print('Error evaluating column named: %s' % column_name)
             ans = error_value + ' ' + e.message
         return ans