Why does this give me VCR::Errors::UnhandledHTTPRequestError

Gemfile

source 'https://rubygems.org'

group :development do
  gem 'rake'
  gem 'guard', require: false
  gem 'guard-rspec', require: false
end

group :development, :testing do
  gem 'dotenv'
end

group :testing do
  gem 'rspec'
  gem 'vcr'
  gem 'webmock'
end

spec_helper.rb

require 'vcr'

RSpec.configure do |config|
  config.extend VCR::RSpec::Macros
  
  config.expect_with :rspec do |expectations|
    expectations.include_chain_clauses_in_custom_matcher_descriptions = true
  end

  config.mock_with :rspec do |mocks|
    mocks.verify_partial_doubles = true
  end

  # Tag tests with :focus to only run them.
  config.filter_run :focus
  config.run_all_when_everything_filtered = true

  # Allows RSpec to persist some state between runs in order to support
  # the `--only-failures` and `--next-failure` CLI options. We recommend
  # you configure your source control system to ignore this file.
  config.example_status_persistence_file_path = "spec/examples.txt"

  config.disable_monkey_patching!

  config.warnings = false

  if config.files_to_run.one?
    # Use the documentation formatter for detailed output,
    # unless a formatter has already been configured
    # (e.g. via a command-line flag).
    config.default_formatter = 'doc'
  end

  # Print the 10 slowest examples and example groups at the
  # end of the spec run, to help surface which specs are running
  # particularly slow.
  config.profile_examples = 10

  config.order = :random

  Kernel.srand config.seed

end

VCR.configure do |config|
  config.cassette_library_dir = 'fixtures/vcr_cassettes'
  config.debug_logger = File.open('vcr_log.txt', 'w')
  config.hook_into :webmock
  #config.default_cassette_options = { record: :new_episodes }
end

the_spec.rb

require 'spec_helper'

RSpec.describe ProductClient do
  before(:all) do
    @client = ProductClient.new
    @products = Array JSON.parse(File.read('spec/fixtures/products.json'))
  end

  context '#index', :focus do
    VCR.use_cassette('index') do
      before(:all) { @response = @client.index }
      subject { @response }

      it 'is successful' do
        expect(@response).to be_kind_of Hash
        expect(@response['errors']).to be_nil
      end
    end
  end
end

VCR_log.txt

[Cassette: 'index'] Initialized with options: {:record=>:once, :match_requests_on=>[:method, :uri], :allow_unused_http_interactions=>true, :serialize_with=>:yaml, :persist_with=>:file_system}
[webmock] Handling request: [get http://0.0.0.0:3000/api/products?page=1] (disabled: false)
[webmock] Identified request type (unhandled) for [get http://0.0.0.0:3000/api/products?page=1]