message: refactor: delete deadcode / improve coverage
diff: @@ -11,7 +11,6 @@ const reqResMapper = (event, callback) => {
  };
  const req = new Stream.Readable();
  - req._read = f => f;
  req.url = (event.requestContext.path || event.path || "").replace(
  new RegExp("^/" + event.requestContext.stage),
  ""
  @@ -27,7 +26,7 @@ const reqResMapper = (event, callback) => {
  const headers = event.multiValueHeaders || {};
  - for (const key of Object.keys(headers || {})) {
  + for (const key of Object.keys(headers)) {
  for (const value of headers[key]) {
  req.rawHeaders.push(key);
  req.rawHeaders.push(value);
  @@ -81,7 +80,7 @@ const reqResMapper = (event, callback) => {
  response.body = Buffer.from(response.body).toString(
  base64Support ? "base64" : undefined
  );
  - response.multiValueHeaders = res.headers || {};
  + response.multiValueHeaders = res.headers;
  res.writeHead(response.statusCode);
  fixApiGatewayMultipleHeaders();
  callback(null, response);
  