Improve the logs to include a message

log.error() takes either one parameter (an object use to print some content
with toString) or two (one object and the exception).
As only one argument was used here, the behaviour was probably not the one
expected by the developer who wrote this code.
It should now be fixed.
Merge pull request #5 from ox-it/logs

WL-2962 Improve the logs to include a message