Stacktrace Data can be an array

[nwestfall]

I've noticed that in one of my test files, the stacktrace data was actually being parsed as an array, instead of a string causing this error

Payload

{
  _attributes: {
    name: 'Response time is less than 1000ms',
    time: '6.287',
    classname: 'REDACTED'
  },
  failure: {
    _attributes: {
      type: 'AssertionFailure',
      message: 'expected 6287 to be below 1000'
    },
    _cdata: [
      'Failed 1 times.',
      'Collection JSON ID: REDACTED.',
      'Collection name: REDACTED.',
      'Request name: REDACTED.',
      'Test description: Response time is less than 1000ms.',
      'Error message: expected 6287 to be below 1000.',
      'Stacktrace: AssertionError: expected 6287 to be below 1000\n' +
        '   at Object.eval sandbox-script.js:2:1).'
    ]
  }
}

Going to parse results form tests/postman-node/newman/*.xml
Error: ((testcase.failure && testcase.failure._cdata) || (testcase.failure && testcase.failure._text) || (testcase.error && testcase.error._cdata) || (testcase.error && testcase.error._text) || "").trim is not a function

To fix this, simply calling toString before trim, will join the data if it's an Array.

[mikepenz]

Thank you so much for the pr.