in ApplicationBootstrap#setupErrorHandling(). In webrouter.php disable
them unconditionally (until ApplicationBootstrap#setupErrorHandling())
not to duplicate the check. ApplicationBootstrap#setupErrorHandling())
is called pretty early, so we won't miss much.
fixes#5117
* In addition, this provides #5269 and mitigates #5152 in production
where ICINGAWEB_ENVIRONMENT isn't set.