[BUG]: find and findFirst fails with exception from Phalcon\Mvc\Model->toArray if there is APCU model cache enabled

[elcreator]

Describe the bug
find and findFirst fails with exception from Phalcon\Mvc\Model->toArray if there is APCU model cache enabled.

To Reproduce
[06-Oct-2021 23:20:27 Europe/Kiev] PHP Fatal error: Uncaught Error: Typed property Auth\Models\User::$email must not be accessed before initialization in /home/project/includes/BaseModel.php:33
Stack trace:
#0 /home/project/includes/BaseModel.php(33): Phalcon\Mvc\Model->toArray()
#1 [internal function]: BaseModel->toArray()
#2 [internal function]: Phalcon\Mvc\Model->serialize()
#3 [internal function]: serialize()
#4 [internal function]: Phalcon\Mvc\Model\Resultset\Simple->serialize()
#5 [internal function]: serialize()
#6 [internal function]: Phalcon\Storage\Serializer\Php->serialize()
#7 [internal function]: Phalcon\Storage\Adapter\AbstractAdapter->getSerializedData()
#8 [internal function]: Phalcon\Storage\Adapter\Apcu->set()
#9 [internal function]: Phalcon\Cache->set()
#10 [internal function]: Phalcon\Mvc\Model\Query->execute()
#11 /home/project/includes/BaseModel.php(112): Phalcon\Mvc\Model::findFirst()
#12 /home/project/modules/auth/controllers/LoginController.php(22): BaseModel::findFirst()
#13 [internal function]: Auth\Controllers\LoginController->login in /home/project/includes/BaseModel.php on line 33

Steps to reproduce the behavior:
https://github.com/elcreator/phalcon-demo/blob/main/includes/BaseModel.php#L117 - uncomment this to see the failure.
It works if these lines remain commented (i.e. when cache parameter is absent).
Refer to https://docs.phalcon.io/4.0/en/db-models-cache example as cache was taken from this doc

Expected behavior
Error should not be thrown

Details

• Phalcon version: (php --ri phalcon) 5.0.0alpha6
• PHP Version: (php -v) 7.4
• Operating System: Ubuntu 20
• Installation type: pear install
• Zephir version (if any): 0.14.0-beta.3-0be9ad5
• Server: Nginx
• Other related info (Database, table schema): MySQL

Additional context
https://github.com/elcreator/phalcon-demo follow readme to get environment with DB to reproduce this issue when trying to login

Get familiar with https://github.com/elcreator/phalcon-demo/blob/main/modules/auth/controllers/LoginController.php
https://github.com/elcreator/phalcon-demo/blob/main/modules/auth/models/EmailUser.php
https://github.com/elcreator/phalcon-demo/blob/main/modules/auth/models/User.php

[BeMySlaveDarlin]

This is related to how typed properties works in php7.4+ and the way we initialize models.
For now, to fix this issue, we need to change the logic of models initializasion in Phalcon\Mvc\Model::unserialize().
Highly likely it will cause bbc.