Add non regression test for 3761

[VincentLanglet]

Rules about unreachable branch was removed in
7d74a63...cc7ff8b

The error doesn't exists anymore
https://phpstan.org/r/788cdf82-69e5-450b-8851-f475793aadcc

I added the test regression to ensure we won't get the following error
https://phpstan.org/r/b888b1ec-063b-49dc-8db8-daa1a0495200

Closes phpstan/phpstan#3761

[ondrejmirtes]

Please reference the issue with "Closes ..." in the PR description.

[ondrejmirtes]

Also I don't really get it - playground still reports the error https://phpstan.org/r/b888b1ec-063b-49dc-8db8-daa1a0495200, how could you add a regression test if it still needs fixing?

[VincentLanglet]

Also I don't really get it - playground still reports the error phpstan.org/r/b888b1ec-063b-49dc-8db8-daa1a0495200, how could you add a regression test if it still needs fixing?

I edited to change

if($tag instanceof $class){

into

if($tag instanceof NamedTag){

to show what would happen with the previous understanding of PHPStan. (and what message we would have got, and therefor in which testCase i have to put the test)

[VincentLanglet]

Please reference the issue with "Closes ..." in the PR description.

Sorry, I forgot, I added the phpstan/phpstan#3761 reference.