Following code case payload in key: method end produces such AST (with Parser::CurrentRuby.parse, using Parser::Ruby27 parser gem version: 2.7.0.1): s(:case_match, s(:send, nil, :payload), s(:in_pa...

Rubocop brakes on 2.7 pattern matching AST nodes while tree walking, as they children may be `nil` · Issue #7624 · rubocop/rubocop