Log sign errors

src/Ui/UiWebsocket.py

@@ -382,6 +382,7 @@ class UiWebsocket(object):
         except Exception, err:
             self.cmd("notification", ["error", _["Content signing failed"] + "<br><small>%s</small>" % err])
             self.response(to, {"error": "Site sign failed: %s" % err})
+            self.log.error("Site sign failed: %s: %s" % (inner_path, Debug.formatException(err)))
             return
 
         site.content_manager.loadContent(inner_path, add_bad_files=False)  # Load new content.json, ignore errors