Whenever user has a role with subtree limitation and you don't pass $targets into `canUser` (for example: you are checking if user can create a content in language, you don't care about location yet).
My use case is that I want to restrict language list for creating new content but I don't necessarily have Location to check with.
This is caused because:
1. PermissionResolver:canUser is overriding $targets to null if it's empty
2. SubtreeLimitation::evaluateForContentCreateStruct is expecting an array but it's getting null.
The comment in SubtreeLimitation::evaluateForContentCreateStruct reads
However it never reaches that point. It would be an expected behavior in my case.