cmd/uninstall: fix Array comparison

In #7526 a comparison for `paths` was introduced, but if `paths` is ever
`nil`, this triggers an error.

Coercing the variable to an Array should alleviate this problem, as
`nil.to_a` produces an empty and comparable Array.

Fixes #7540

Signed-off-by: Mike Fiedler <miketheman@gmail.com>

Library/Homebrew/cmd/uninstall.rb

@@ -92,7 +92,7 @@ module Homebrew
             end
 
             unversioned_name = f.name.gsub(/@.+$/, "")
-            maybe_paths = Dir.glob("#{f.etc}/*#{unversioned_name}*") - paths
+            maybe_paths = Dir.glob("#{f.etc}/*#{unversioned_name}*") - paths.to_a
             if maybe_paths.present?
               puts
               opoo <<~EOS