warning: already initialized constant REXML:: warnings with guard-brakeman

[ndbroadbent]

See: presidentbeef/brakeman#1705

I noticed that adding the guard-brakeman gem to my Gemfile (in the development group) causes lots of these warnings to appear in my logs:

/Users/ndbroadbent/.rbenv/versions/2.7.5/lib/ruby/gems/2.7.0/gems/brakeman-5.4.0/bundle/ruby/2.7.0/gems/rexml-3.2.5/lib/rexml/parsers/baseparser.rb:30: warning: already initialized constant REXML::Parsers::BaseParser::LETTER
/Users/ndbroadbent/.rbenv/versions/2.7.5/lib/ruby/gems/2.7.0/gems/rexml-3.2.5/lib/rexml/parsers/baseparser.rb:30: warning: previous definition of LETTER was here
/Users/ndbroadbent/.rbenv/versions/2.7.5/lib/ruby/gems/2.7.0/gems/brakeman-5.4.0/bundle/ruby/2.7.0/gems/rexml-3.2.5/lib/rexml/parsers/baseparser.rb:31: warning: already initialized constant REXML::Parsers::BaseParser::DIGIT
/Users/ndbroadbent/.rbenv/versions/2.7.5/lib/ruby/gems/2.7.0/gems/rexml-3.2.5/lib/rexml/parsers/baseparser.rb:31: warning: previous definition of DIGIT was here
/Users/ndbroadbent/.rbenv/versions/2.7.5/lib/ruby/gems/2.7.0/gems/brakeman-5.4.0/bundle/ruby/2.7.0/gems/rexml-3.2.5/lib/rexml/parsers/baseparser.rb:33: warning: already initialized constant REXML::Parsers::BaseParser::COMBININGCHAR
/Users/ndbroadbent/.rbenv/versions/2.7.5/lib/ruby/gems/2.7.0/gems/rexml-3.2.5/lib/rexml/parsers/baseparser.rb:33: warning: previous definition of COMBININGCHAR was here
/Users/ndbroadbent/.rbenv/versions/2.7.5/lib/ruby/gems/2.7.0/gems/brakeman-5.4.0/bundle/ruby/2.7.0/gems/rexml-3.2.5/lib/rexml/parsers/baseparser.rb:34: warning: already initialized constant REXML::Parsers::BaseParser::EXTENDER
...

[ryankon]

@ndbroadbent I ran into this issue as well. It was caused by not setting required: false for rubocop and rubocop-rails.