code: function createJsonError(attribute) {
      const name = !attribute
        ? node.type
        : `${node.type} with ${attribute}=${JSON.stringify(node[attribute])}`;
      return createError(`${name} is not allowed in JSON.`, {
        start: {
          line: node.loc.start.line,
          column: node.loc.start.column + 1
        }
      });
    }
docs: istanbul ignore next