Possible bug in mergeRequestParams when --axios is used

[kamzcgcg]

Summary:
I believe I identified a bug in the generated code when axios is enabled:

  private mergeRequestParams(params1: AxiosRequestConfig, params2?: AxiosRequestConfig): AxiosRequestConfig {
    return {
      ...this.instance.defaults,
      ...params1,
      ...(params2 || {}),
      headers: {
        ...this.instance.defaults, // this should be ...this.instance.defaults.headers
        ...(params1.headers || {}),
        ...((params2 && params2.headers) || {}),
      },
    };
  }

line ...this.instance.defaults,

should become

...this.instance.defaults.headers

How to reproduce:

I have debugged the generated code and found that I can reproduce the issue by creating a sample axios code and utilize the mergeRequestParams that was generated by swagger-typescript-api.

Here's a sample code to show the issue:

import axios, {  AxiosRequestConfig } from "axios";

// function copied from the generated code.
function mergeRequestParams(defaultParams: AxiosRequestConfig, params1: AxiosRequestConfig, params2?: AxiosRequestConfig): AxiosRequestConfig {
  return {
    ...defaultParams,
    ...params1,
    ...(params2 || {}),
    headers: {
      ...defaultParams,
      ...(params1.headers || {}),
      ...((params2 && params2.headers) || {}),
    },
  };
}

(async () => {
  try {

    const client = axios.create({

      transformRequest: [(data, headers) => { return data; }],   // Without this I get: Invalid character in header content ["transformRequest"] 
      transformResponse: [(data, headers) => { return data; }], // Without this I get: Invalid character in header content ["transformResponse"] 

      baseURL: "https://localhost:7001/",
    });

    const requestParams = mergeRequestParams(client.defaults, {}, {})

    client.request({
      ...requestParams,
      headers: {
        "Content-Type": "application/json",
        ...requestParams.headers,
      },
      params: {date:'2020-03-31'},
      responseType: 'json',
      url: '/overview',
    });

  } catch (e) {
    console.log( e);
  }
})();

The error I get here is:

(node:60845) UnhandledPromiseRejectionWarning: TypeError [ERR_INVALID_CHAR]: Invalid character in header content ["adapter"]
    at ClientRequest.setHeader (_http_outgoing.js:529:3)
    at new ClientRequest (_http_client.js:241:14)
    at Object.request (https.js:314:10)
    at RedirectableRequest._performRequest (/Users/kamz/workspace/clarity/clarity-model/node_modules/follow-redirects/index.js:262:24)
    at new RedirectableRequest (/Users/kamz/workspace/clarity/clarity-model/node_modules/follow-redirects/index.js:60:8)
    at Object.request (/Users/kamz/workspace/clarity/clarity-model/node_modules/follow-redirects/index.js:458:14)
    at dispatchHttpRequest (/Users/kamz/workspace/clarity/clarity-model/node_modules/axios/lib/adapters/http.js:195:25)
    at new Promise (<anonymous>)
    at httpAdapter (/Users/kamz/workspace/clarity/clarity-model/node_modules/axios/lib/adapters/http.js:46:10)
    at dispatchRequest (/Users/kamz/workspace/clarity/clarity-model/node_modules/axios/lib/core/dispatchRequest.js:52:10)
(node:60845) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 3)
(node:60845) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

[js2me]

@kamzcgcg fixed in 6.4.1, thanks for report!