undefined method `=~' for [:ReturnEnvelope, :Boolean]:Array (NoMethodError)

[elcous]

ETHON: Libcurl initialized
ETHON: performed EASY effective_url=https://api.lob.com/v1/letters response_code=200 return_code=ok total_time=0.519936
/Users/.../.local/share/mise/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/lob-6.0.9/lib/lob/models/letter.rb:609:in `block in build_from_hash': undefined method `=~' for [:ReturnEnvelope, :Boolean]:Array (NoMethodError)

to recreate

with test credentials Create a letter

def call
      letter_api = Lob::LettersApi.new
      response = letter_api.create(letter_params)
    end

    private

    def letter_params
      Lob::LetterEditable.new(
        description:,
        to: address_params(to_address),
        from: address_params(from_address),
        file: html_content,
        merge_variables:,
        color: false,
        use_type: 'operational'
      )
    end

    def address_params(address)
      # rubocop:disable Naming/VariableNumber
      Lob::AddressEditable.new(
        name: address.name,
        address_line1: address.street_address,
        address_line2: address.street_address_2,
        address_city: address.city,
        address_state: address.state,
        address_zip: address.zip_code
      )
      # rubocop:enable Naming/VariableNumber
    end