Clients may send optional params as an explicit JSON null rather than
omitting them; Amethyst does for description, description_hash and
expiry. dict.get only applies its default for a missing key, so
description arrived as None and make_invoice failed with
"'NoneType' object has no attribute 'encode'".
Coerce with `or` instead, pass no unhashed_description when the
description is blank, and apply the same to list_transactions' paging
params, which had the same exposure.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013Tbyw6FwjhEJg3gHfPHxWt
