Add non regression test

[VincentLanglet]

Both #5203 and #5189 seems to break the following snippet.

It might be simpler to

• merge this regression test
• close the PRs
• reopen them with the bot

WDYT @staabm ?

[staabm]

I had a similar idea. I think we can merge this test.

I would make it smaller though: https://phpstan.org/r/50723b9b-06bc-4d7d-b1e1-5692ca02ca84

(and maybe rebase open PRs instead of starting from square-1 is enough)

[staabm]

thanks