When, in a template, you try to access legacy variables using ezpublish.legacy, it raise an error.

Steps to reproduce:
in a template (ex: pagelayout.html.twig), try to display {{ ezpublish.legacy.get( 'path' ) }} and you will get an error like this :

ContextErrorException: Warning: array_key_exists() expects parameter 2 to be array, null given in /Users/huckflorent/Sites/e-learning/vendor/symfony/symfony/src/Symfony/Component/HttpFoundation/ParameterBag.php line 106

And if you just dump ezpublish.legacy, metadata parameters is null.

maybe this is linked to https://jira.ez.no/browse/EZP-22897?jql=text%20~%20%22ezpublish.legacy%22
?

Best