The raw response: a lastModified timestamp, a contentList and one entry per
country. A 2xx answer without any country entry, with an error member, or whose
contentList names ids without an entry is a ReiseParseError (see checkList), never an
empty result.
The list flattened to an array of country entries (each carrying its content
id), with the lastModified envelope key dropped. With warnedOnly: true,
only the countries isWarned accepts (any of the four flags true).
A warnedOnly that is not a boolean, options that are not an object, and an unknown
option key (a misspelt warnedonly) are rejected with a ReiseValidationError before
any request.
One country's warning flags plus every sentence of its advisory that warns or advises against something (see TravelAdvice) — the part of the 40–70 KB HTML a travel-safety verdict depends on, because the flags record only the formal warning levels. Fetches the advisory with get (same errors, same id rule); an entry without
contentis a ReiseParseError, never an advisory without advice.