fix(zenroom): initialize zenroom before script check, in this way the error on empty script follows the logfmt specification

[matteo-cristino]

• fix(zenroom): initialize zenroom before script check, in this way the error on empty script follows the logfmt specification
• test(js): update error returned by empty script

[matteo-cristino]

There are still some _err() calls that does not follow the logfmt specified in the conf, but these can not be directly substituted with zerror() since are zenroom or lua initialization error. Another solution should be found for these cases to report errors with the right format.