Further improvement of error handling for LZString

This does some more in depth check on the error message and minimizes
the log noise that is caused by LZString.

Signed-off-by: Sheogorath <sheogorath@shivering-isles.com>

lib/history.js

@@ -47,7 +47,11 @@ function getHistory (userid, callback) {
           }
         } catch (err) {
           // most error here comes from LZString, ignore
-          logger.error(err)
+          if (err.message === 'Cannot read property \'charAt\' of undefined') {
+            logger.warning('Looks like we can not decode "' + history[i].id + '" with LZString. Can be ignored.')
+          } else {
+            logger.error(err)
+          }
         }
       }
       history = parseHistoryToObject(history)