Enabling the plugin hides some errors

[LeSuisse]

Hi,

It seems that when the plugin is active some errors are not visible, for example with the following test class I would have expected to get an InvalidReturnType and an InvalidReturnStatement errors but instead no errors are thrown:

<?php

declare(strict_types=1);

namespace Repro;

use PHPUnit\Framework\TestCase;

final class ReproTest extends TestCase
{
    use \Mockery\Adapter\Phpunit\MockeryPHPUnitIntegration;

    public function dataProviderCoveringScopes(): bool
    {
        return ['foo'];
    }
}

I have set up a repo that can be used to reproduce: https://github.com/LeSuisse/repro-issue-psalm-mockery-issue-no-error