toJson() fails on ApiContext of an user person due to session context

[OGKevin]

Steps to reproduce:

1. Make an ApiContext with an UserPerson API key
2. Call the toJson() method on this context

What should happen:

1. The user will get a JSON representation of the ApiContext

What happens:

1. You will get the following error:

Return value of bunq\Model\Core\SessionServer::getUserCompany() must be an instance of bunq\Model\Generated\Endpoint\UserCompany, null returned
 /Users/khellemun/GitHub/bunq/sdk_php/src/Model/Core/SessionServer.php:79
 /Users/khellemun/GitHub/bunq/sdk_php/src/Context/SessionContext.php:76
 /Users/khellemun/GitHub/bunq/sdk_php/src/Context/SessionContext.php:64
 /Users/khellemun/GitHub/bunq/sdk_php/src/Context/SessionContext.php:52
 /Users/khellemun/GitHub/bunq/sdk_php/src/Context/ApiContext.php:164
 /Users/khellemun/GitHub/bunq/sdk_php/src/Context/ApiContext.php:123
 /Users/khellemun/GitHub/bunq/sdk_php/src/Context/ApiContext.php:110
 /Users/khellemun/GitHub/bunq/sdk_php/tests/BunqSdkTestBase.php:64
 /Users/khellemun/GitHub/bunq/sdk_php/tests/Context/ApiContextTest.php:22

Extra info:

• Tested on https://github.com/bunq/sdk_php/tree/0.12.0

[basst85]

Thanks for writing this issue 👍