OptionaldetectChoose the language of each HTTP handler response from the request.
true (default) uses the Accept-Language header; a function returns a
language (or undefined for the default); false always uses locale.
OptionalfallbackUsed for codes missing in a language. Default: 'en'
OptionallocaleDefault language. Default: 'en'
OptionalmessagesMore languages, or overrides of the built-in messages, by language:
{ tr: { INSUFFICIENT_FUNDS: '...' }, de: { ... } }. Keys are normalized
error codes, or codes declared by plugins in $ERROR_CODES.
better-payment/plugins: official plugins.