Implicit has one relation not working

[xjuric29]

Version: v3.0.2

Bug Description

"Implicit has one" access doesn't work with correct foreign key references.

Steps To Reproduce

Access any table column from table linked with foreign key like this:
$ticket->user->first_name

Longer notation with ref is working:
$ticket->ref('user', 'author')->first_name

Expected Behavior

Implicit access should work exactly like calling method ref() as described at https://doc.nette.org/cs/3.0/database-explorer