PHP - Different class property values ​​with and without php extension

[s2x]

What version of protobuf and what language are you using?
Version: 4.28.3
Language: PHP

What operating system: Linux - Ubuntu 24.04

What did you do?
Steps to reproduce the behavior:
proto:

message TestOptional {
  optional string test = 1;
}

php

$test = new TestOptional();

$refl = new \ReflectionProperty($test, 'test');
var_dump([
    'getter' => $test->getTest(),
    'has' => $test->hasTest(),
    'ref_val' => $refl->getValue($test),
]);

What did you expect to see
without extension:

array(3) {
  ["getter"]=>
  string(0) ""
  ["has"]=>
  bool(false)
  ["ref_val"]=>
  NULL <---- HERE
}

with extension:

array(3) {
  ["getter"]=>
  string(0) ""
  ["has"]=>
  bool(false)
  ["ref_val"]=>
  string(0) "" <---- HERE
}

In most of my code, this behavior has no impact on the code working properly. However, when I use Symfony Validator, which iterates over class properties, the system behaves differently with and without the extension.

Additionally, with the extension enabled we get a segmentation fault when we want to check a non-existent property. For example when we will ask for test1 field:

$refl = new \ReflectionProperty($test, 'test1');

result:

 4298 segmentation fault (core dumped)