Can't make code_ownership and code_teams gems to work

The gems code_teams, code_ownership should allow one to tag files/whole folders by team name but after adding them to my project, running bundle install etc, I still encounter the same error

Passed `nil` into T.must

sample team file (placed in config/teams as advised) is as following

name: Smurfs
owned_globs:
  - folder/filename1.rb

The code where I try to use the info is :

x = CodeOwnership.for_backtrace(e.backtrace)