[php-src] Issue #9929: assert() AssertionError message is not helpful

Issue: https://github.com/php/php-src/issues/9929 Author: oojacoboo ### Description Currently, the following code: ```php $foo = new Bar; assert($foo instanceof Foo); ``` Results in a message from AssertionError... > assert($foo instanceof Foo) This error message really isn't helpful. It doesn't provide you any context into the variable values or types such that the error can be resolved. It requires manually debugging the error. At the very least, I'd suggest that, if an assertion fails, all variables used in the assertion, at least have their type output in the error message somehow.