pub const CODE_UNSUPPORTED: i32 = -2;Expand description
CHS_CODE_UNSUPPORTED from include/chtypes.h: “this build refuses to
answer”, and never a real ClickHouse error code.
Mapping it onto a rejection manufactures an over-reject the product never made; mapping it onto an acceptance manufactures an over-accept, which is the cardinal sin. It is exposed here so a caller can branch on it.