IBX-3823: Fixed appending limitations, when there are no initial values

[ViniTou]

Question	Answer
JIRA issue	IBX-3823
Type	bug
Target Ibexa version	v3.3
BC breaks	no

As when there were no limitations assigned to policy, $previousPolicyMap[$module][$function] is null, and array_merge_recursive was throwing type error.

This could be reproduced with new PolicyProviderInterface for example with:

    public function addPolicies(ConfigBuilderInterface $configBuilder)
    {
        $configBuilder->addConfig([
            'setup' => [
                'administrate' => ['SiteAccess'],
            ],
        ]);
    }

Checklist:

• Provided PR description.
• Tested the solution manually.
• Provided automated test coverage.
• Checked that target branch is set correctly (master for features, the oldest supported for bugs).
• Ran PHP CS Fixer for new PHP code (use $ composer fix-cs).
• Asked for a review (ping @ezsystems/engineering-team).

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[micszo]

QA Approved on Ibexa Commerce 3.3.27-dev.