Readonly liskov violations in new Dom API

Description

The following code:

<?php
$xml = <<<END
<?xml version="1.0" encoding="UTF-8"?>
<root>
    <child />
</root>
END;

$doc = Dom\XMLDocument::createFromString($xml);
$root = $doc->firstChild;
$text = $root->firstChild;
$child = $root->firstElementChild;

try {
    $text->nodeValue = 'Hello';
} catch (Throwable $t) {
    var_dump($t->getMessage());
}

try {
    $child->nodeValue = 'Hello';
} catch (Throwable $t) {
    var_dump($t->getMessage());
}

try {
    $doc->nodeValue = 'Hello';
} catch (Throwable $t) {
    var_dump($t->getMessage());
}


try {
    $text->textContent = 'Hello';
} catch (Throwable $t) {
    var_dump($t->getMessage());
}

try {
    $child->textContent = 'Hello';
} catch (Throwable $t) {
    var_dump($t->getMessage());
}

try {
    $doc->textContent = 'Hello';
} catch (Throwable $t) {
    var_dump($t->getMessage());
}

Resulted in this output:

string(55) "Cannot modify readonly property Dom\Element::$nodeValue"
string(59) "Cannot modify readonly property Dom\XMLDocument::$nodeValue"
string(61) "Cannot modify readonly property Dom\XMLDocument::$textContent"

But I expected this output instead:

In user code this would result in:

Fatal error: Cannot redeclare non-readonly property X::$y as readonly Y::$y

Since I've found multiple of these exploring the new Dom API it probably needs a closer look.

Tested in both docker (php:8.4-rc-alpine version 8.4.0beta3) and 3v4l

PHP Version

8.4.0beta3

Operating System

No response

Start by reproducing the readonly-property behavior from the issue's PHP example against the new Dom API, then inspect the declarations and inheritance relationships for nodeValue and textContent on Dom\Element and Dom\XMLDocument. Done means the reported Liskov-compatibility violations are resolved without the fatal readonly-property errors shown.