[BUG] Javascript babel, weird output for comment block

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Bounty to sponsor the fix (example)

Description

Using the javascript client module, when using npm run build, the first block comment in the files in src get distorted with a lot of blank spaces and renders navigation of the code really slow.

Initial block comment:

/**
 * Custom API
 * Custom API
 *
 * OpenAPI spec version: 0.0.1
 * 
 *
 * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
 * https://openapi-generator.tech
 * Do not edit the class manually.
 *
 */

Block comment modified by babel and code added:

"use strict";

Object.defineProperty(exports, "__esModule", {
    value: true
});

var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) { return typeof obj; } : function (obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; };

var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }(); /**
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      * Custom API
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      * Custom API
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      *
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      * OpenAPI spec version: 0.0.1
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      * 
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      *
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      * https://openapi-generator.tech
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      * Do not edit the class manually.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      *
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      */

Removing the .babelrc appears to prevent this distorsion.

openapi-generator version

4.0.0-beta3

OpenAPI declaration file content or url

openapi: 3.0.0
info:
  title: Custom API
  description: Custom API
  version: 0.0.1
servers:
- url: "/api/v1"
paths:
  /custom:
    get:
      summary: Returns a custom object
      operationId: app.custom
      responses:
        '200':
          description: Custom found
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/object'
        '404':
          description: Custom not found

components:
  schemas:
    object:
      description: Custom value
      type: number

Command line used for generation

npx openapi-generator generate --skip-validate-spec -i custom.yml -g javascript -o custom_api_javascript

Steps to reproduce

After generating the module:

cd custom_api_javascript
npm install
npm run build

Related issues/PRs

None

Suggest a fix

Remove .babelrc, but it might be used for other things.

Start with the generated JavaScript module's .babelrc and the files under src, then reproduce the issue with npm install and npm run build after generation with the provided command. Done means the first block comment remains readable without the large inserted indentation while the generated module still builds successfully.