GUACAMOLE-527: Remove unused error message length variable.
GUACAMOLE-527: Remove unused error message length variable.

apache/guacamole-server,mike-jumper/incubator-guacamole-server,glyptodon/guacamole-server,glyptodon/guacamole-server,apache/guacamole-server,mike-jumper/incubator-guacamole-server,glyptodon/guacamole-server,mike-jumper/incubator-guacamole-server,apache/guacamole-server,mike-jumper/incubator-guacamole-server