Bug report

In a if statement, I first check that affectation of a variable is not NULL, and then try to use the variable in a second part of the condition. PHPStan output an error like Undefined variable: $affectedVar.

It could be related to #4357.

Code snippet that reproduces the problem

https://phpstan.org/r/43c76836-a07b-40ef-826f-e72c889b9024

Expected output

In the above example, PHPStan should not output that $programStartDate is undefined at line 22.