`ConsoleOutputFileReporter` attributes output without stack trace to a default `null` report

[pshevche]

Affected version

3.6.0+

Bug description

The regression was introduced with #3179. See this comment for an analysis of the issue. I observed this behavior when using the redirectTestOutputToFile property. The issue may be specific to the Develocity Maven extension, so I am not sure you'd be able to reproduce it easily with the default Surefire executor. However, the fix seems straightforward.