Merge pull request #20948 from Homebrew/fix-outdated-check-on-missing-core-formula

Don't fail if a formula stub doesn't exist when checking `Formula#outdated?`

Author: MikeMcQuaid

Library/Homebrew/formula.rb

@@ -1743,7 +1743,7 @@ def outdated_kegs(fetch_head: false)
     Formula.cache[:outdated_kegs][cache_key] ||= begin
       all_kegs = []
       current_version = T.let(false, T::Boolean)
-      latest = if core_formula? && Homebrew::EnvConfig.use_internal_api?
+      latest = if core_formula? && Homebrew::EnvConfig.use_internal_api? && Homebrew::API.formula_names.include?(full_name)
         Homebrew::API::Internal.formula_stub(full_name)
       else
         latest_formula