This would be during formal testing, which is similar to what you might know as “acceptance testing”. The spacecraft doesn’t “enter safe mode” during development.

If you’re paying two billion $ for something you become very very interested in test design and test results.

Also, safe mode isn’t really the same as a BSOD. It’s a mode where the spacecraft decides something is wrong and disables a lot of functionality and focuses on pointing the solar panels at the sun and the antennas at the ground. It does not cease functioning - if that happens, you’ve probably lost your spacecraft. It is therefore VITALLY IMPORTANT that safe mode works, and a smart program manager tests the hell out of it.