null coalesce inside is_string() on optional array key has issues #8076
Description
Bug report
Code snippet that reproduces the problem
https://phpstan.org/r/f0b56620-fd83-4fd4-9c03-9e85afdfa2c3
Expected output
No errors
{{ message }}
https://phpstan.org/r/f0b56620-fd83-4fd4-9c03-9e85afdfa2c3
No errors