Variable flagged as "might not be defined" when declared before an exception can be thrown. #4838
Description
Bug report
When a variable is set in a block that later in the block throws an error, a "variable might not be set" error is raised incorrectly.
Code snippet that reproduces the problem
https://phpstan.org/r/8dbd457d-5547-483e-972c-ff5d32725d20
Expected output
No errors were found.