send Mysqlx.Sql.StmtExecute {
  stmt: "whatever"
  namespace: "xplugin"
}

Got expected error: Invalid xplugin command whatever (code 5157)
send Mysqlx.Sql.StmtExecute {
  stmt: "whatever"
  namespace: "bogus"
}

Mysqlx.Error {
  severity: ERROR
  code: 5162
  msg: "Unknown namespace bogus"
  sql_state: "HY000"
}

Mysqlx.Ok {
  msg: "bye!"
}
ok