Client drivers act differently on errors codes they don't recognize. Adding new errors codes is considered a protocol extension and should be negotiated with the client. This change keeps `overflow_error_exception` internally but uses the INVALID cql error code to return the error message back to the client similar to keyspace_not_defined_exception. We (and cassandra) already use `invalid_request_exception` extensively to return various errors related to invalid values or types in the query. Fixes #6264 Signed-off-by: Benny Halevy <bhalevy@scylladb.com> Reviewed-by: Gleb Natapov <gleb@scylladb.com> Message-Id: <20200422130011.108003-1-bhalevy@scylladb.com>