We faced this issue during upgrade to eZ Platform v3 from eZ Publish. And seems like the only ezcontent:// links are used in eZ Platform v3, which makes hard to reproduce it on the clean eZ Platform v3.0.3 installation.

Steps to reproduce
1. Create a new Article, and embed location in its RichText field. The simplest way is to use https://gitlab.com/contextualcode/ezplatform-alloyeditor-source and add the following HTML:

<div data-ezelement="ezembed" data-href="ezlocation://2" data-ezview="embed" data-ez-node-initialized="true">&nbsp;</div>

2. Save the new article and open its full view page.

Expected result
Embed location will be rendered

Actual result
The following exception is thrown:

Argument 4 passed to eZ\Publish\Core\Repository\Permission\CachedPermissionService::canUser() must be of the type array, object given, called in XXX/vendor/ezsystems/ezplatform-kernel/eZ/Publish/Core/MVC/Symfony/Security/Authorization/Voter/ValueObjectVoter.php on line 63