Undefined variable: current_controller

[nijel]

Error from production environment:

Notice (8): Undefined variable: current_controller in [/home/reports/error-reporting-server/src/Template/Layout/default.ctp, line 85]
Request URL: /incidents/create
Client IP: [hidden]
Trace:
Cake\Error\BaseErrorHandler::handleError() - CORE/src/Error/BaseErrorHandler.php, line 153
include - APP/Template/Layout/default.ctp, line 85
Cake\View\View::_evaluate() - CORE/src/View/View.php, line 1011
Cake\View\View::_render() - CORE/src/View/View.php, line 972
Cake\View\View::renderLayout() - CORE/src/View/View.php, line 643
Cake\View\View::render() - CORE/src/View/View.php, line 601
Cake\Controller\Controller::render() - CORE/src/Controller/Controller.php, line 623
Cake\Error\ExceptionRenderer::_outputMessage() - CORE/src/Error/ExceptionRenderer.php, line 325
Cake\Error\ExceptionRenderer::render() - CORE/src/Error/ExceptionRenderer.php, line 200
Cake\Error\ErrorHandler::_displayException() - CORE/src/Error/ErrorHandler.php, line 137
Cake\Error\BaseErrorHandler::handleException() - CORE/src/Error/BaseErrorHandler.php, line 187
Cake\Error\BaseErrorHandler::wrapAndHandleException() - CORE/src/Error/BaseErrorHandler.php, line 171
[main] - [internal], line ??