Bug report

I expected that when is_numeric returns true for a variable, that variable can be used in a mathematical expression, but it results in Binary operation between string and x results in error.

Also: Thank you for phpstan!

Code snippet that reproduces the problem

https://phpstan.org/r/e58d476f-a25b-480d-8df7-8c869da92f9a

Expected output

No errors.