Fix Windows GitHub Actions transient failures

We've been experiencing lately some transient failures with rspec tests on Windows GitHub Actions. It takes about 16 minutes to fail, whereas successful runs happen in about 18 minutes, so this happens very late and can easily become annoying.

Over 900 tests (958 seen so far) across multiple files fail when this happen (from a total of 26109 examples). Most of them are due to objects being nil and methods cannot be called (around 940).

Attached logs are from are from such failed run (see windows-2016(ruby 2.6) files).