Rails System Tests Error With Webpack

Here's the set up: Rails 5.2, System Test, Webpacker/Webpack for all assets.

test "viewing 2nd page of search results" do
  Capybara::Webkit.configure do |config|
    config.allow_unknown_urls
    config.raise_javascript_errors = true
  end

  50.times do |i|
    Store.create!(name: "Joey's Store #{i}", url: "https://joey#{i}.io")
  end

  visit stores_url

  click_on "Next"

  assert_no_text "Joey's Store 11"
  assert_text "Joey's Store 30"
end

I'm getting this error, any ideas?

Error:
  StoresTest#test_viewing_2nd_page_of_search_results:
  Capybara::Webkit::JavaScriptError: {:line_number=>78, 
    :message=>"ReferenceError: Can't find variable: Set", 
    :source=>"http://127.0.0.1:64990/packs-test/application-c668820b4f1b1eb50cc0.js"}
  test/system/stores_test.rb:23:in `block in <class:StoresTest>'