Fix ChannelCollector related serialization issue in Symfony profiler

[ostrolucky]

Q	A
Branch?	1.4
Bug fix?	yes
New feature?	no
BC breaks?	unlikely, but possible
Deprecations?	no
Related tickets	fixes #10223
License	MIT

This is very annoying long standing issue.

I'm pretty sure this will fix the issue (it does in our case). As a side effect, this is more efficient, as there is less data needed to be serialized.

This issue is related to circular references inside Channel model. In our case we can reproduce with

$n = new Channel();
$locale = new Locale();

$n->addLocale($locale);
$n->setDefaultLocale($locale);

$this->data = [
    'channel' => null,
    'channels' => [$n],
    'channel_change_support' => $channelChangeSupport,
];

inside ChannelCollector

I'm aware changing return type is technically BC break, but it's unlikely somebody uses this class. If this is an issue, please advise how to continue.

[lchrusciel]

Hey Gabriel!

Thanks a lot for your contribution!

@pamil are we ready to make a BC Break here? This class could be consider as internal, but we didn't mention it anywhere.

[pamil]

I think we can proceed with this BC break, it's our internal code and only runs in development environments.

[pamil]

Thanks, Gabriel! 🥇