Array parameters cause fatal errors when not using schemaFaker

[brpeterman]

openapi-to-postmanv2 version: 0.0.12

Example OpenAPI spec:

openapi: 3.0.1
info:
  title: Example API
  version: 1.0.0
paths:
  /operation:
    get:
      summary: Operation that accepts an array
      description: ''
      operationId: operation
      parameters:
        -
          in: query
          name: arrayInput
          schema:
            type: array
            items:
              type: string
      responses:
        default:
          description: Response

Invocation example:

const converter = require('openapi-to-postmanv2');
const fs = require('fs');

const specString = fs.readFileSync('resources/broken.yaml', { encoding: 'utf8' });
this._postman = converter.convert({
    type: 'string',
    data: specString
}, {
    schemaFaker: false
}, () => {});

Description of problem

When schemaFaker is disabled, openapi-to-postmanv2 produces this error for any operation that takes an array parameter that is not annotated with a specific array style:

TypeError: paramValue.join is not a function
    at Object.convertParamsWithStyle (/path/to/project/node_modules/openapi-to-postmanv2/lib/util.js:815:29)

Because schemaFaker is disabled, paramValue is an empty string. It looks like I would also run into this problem in different branches if I did specify an array style, so I don't think that will solve the problem.

I ran into this bug because the schema faker cannot handle recursive schemas and some of the schemas in my API are recursive (tree structures, mainly).