test.err & test.stack is undefined

[marianlorinc]

In case of combination with multi reporters there is a bug.
To sonaqube xml report is not tracked message and stack because they are undefined.

In runner.on('test end') you should handle undefined values for test.stack and test.message:

var mtest = {
           title: test.title,
           titleId: title + ': ' + test.title,
           suite: title,
           stack: test.stack || (test.err && test.err.stack),
           message: test.message || (test.err && `test.err.message),`
           file: file,
           duration: test.duration,
           state: test.state != undefined ? test.state : 'skipped'
       };