Clean up and fix typecheck issue

Library/Homebrew/cmd/link.rb

@@ -45,15 +45,14 @@ module Homebrew
     kegs = if args.HEAD?
       args.named.to_kegs.group_by(&:name).map do |name, resolved_kegs|
         head_keg = resolved_kegs.find { |keg| keg.version.head? }
-        if head_keg.blank?
+        next head_keg if head_keg.present?
+
         opoo <<~EOS
           No HEAD keg installed for #{name}
           To install, run:
             brew install --HEAD #{name}
         EOS
-        end
-        head_keg
-      end.reject(&:blank?)
+      end.compact
     else
       args.named.to_latest_kegs
     end