[Bug]: isset() on a static property no longer compiles: "Cannot use isset() on the result of an expression" #101

Bug report

When a class uses isset(self::$prop) on a static property, the rewritten file does not compile:

Fatal error: Cannot use isset() on the result of an expression (you can use "null !== expression" instead) in src/Holder.php on line 11

It happens with or without a docblock on the property, and also with inline_vars.properties => false. We hit it on a common memoisation pattern (if (!isset(self::$cache)) { self::$cache = ...; }) and it takes the whole test run down, since it is a compile error.

Two files plus composer.json, default config (no typephp.php):

composer.json

{"require": {"typephp/typephp": "0.10.26"}}

src/Holder.php

<?php

namespace App;

class Holder
{
    private static ?string $name = null;

    public function get(): string
    {
        if (!isset(self::$name)) {
            self::$name = self::class;
        }
        return self::$name;
    }
}

run.php

<?php

require __DIR__ . "/vendor/autoload.php";
require __DIR__ . "/src/Holder.php";

echo (new App\Holder())->get(), " OK\n";

Tested on v0.10.26 and on main (88fcb12), PHP 8.2 and 8.3. The type cache was cleared before each run.

Code snippet that reproduces the problem

No playground link: the snippet above is complete.

Expected output

App\Holder OK

Context: same large codebase as #93 / #99; this one stopped a whole module's test suite in CI.