...and before I tried that:
/opt/homebrew/Cellar/ruby/3.4.5/lib/ruby/gems/3.4.0/gems/typeprof-0.30.1/lib/typeprof/lsp/messages.rb:58:in 'TypeProf::LSP::Message::Initialize#run': undefined method 'map' for nil (NoMethodError)
Something fishy is going on, probably unrelated to the homebrew's ruby installation hurdles.
Will add more information as requested, of course, thanks!