🐛 Properly handle XPathParser#document, Child#document # => nil

[pboling]

• Fixes NoMethodError: undefined method 'enable_cache' for nil #260
  • Properly handle XPathParser#document, Child#document returning nil
• Fixes XPath.parse should always return array #262
  • Fixes XPath#first & XPath#each when parser.parse was returning nil
    • parser.parse now returns [] instead of nil when it otherwise would have been nil.

➜  bundle exec rake test
/var/home/pboling/.local/share/mise/installs/ruby/3.4.3/bin/ruby test/run.rb
Loaded suite test
Started
Finished in 3.732624789 seconds.
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
712 tests, 2165 assertions, 0 failures, 0 errors, 0 pendings, 0 omissions, 0 notifications
100% passed
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
190.75 tests/s, 580.02 assertions/s

[kou]

Could you split this PR to logically separated PRs?

For example:

• Refactoring by &. (This must not change the current behavior)
• Caching retrieved doctype in a local variable (This must not change the current behavior)
• Removing redundant return (This must not change the current behavior)
• Reusing XPath.match (This must not change the current behavior)
• Changing XPath.match behavior
• Adding support for Elements#each without document

[pboling]

Sure!