These are all the possible behaviors:

* ``ContainerInterface::EXCEPTION_ON_INVALID_REFERENCE``: throws an exception

at compile time (this is the **default** behavior);

* ``ContainerInterface::RUNTIME_EXCEPTION_ON_INVALID_REFERENCE``: throws an

exception at runtime, when trying to access the missing service;

* ``ContainerInterface::NULL_ON_INVALID_REFERENCE``: returns ``null``;

* ``ContainerInterface::IGNORE_ON_INVALID_REFERENCE``: ignores the wrapping

command asking for the reference (for instance, ignore a setter if the service

does not exist);

* ``ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE``: ignores/returns

``null`` for uninitialized services or invalid references.

* ``ContainerInterface::EXCEPTION_ON_INVALID_REFERENCE``: throws an exception

at compile time (this is the **default** behavior);

* ``ContainerInterface::RUNTIME_EXCEPTION_ON_INVALID_REFERENCE``: throws an

exception at runtime, when trying to access the missing service;

* ``ContainerInterface::NULL_ON_INVALID_REFERENCE``: returns ``null``;

* ``ContainerInterface::IGNORE_ON_INVALID_REFERENCE``: ignores the wrapping

command asking for the reference (for instance, ignore a setter if the service

does not exist);

* ``ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE``: ignores/returns

``null`` for uninitialized services or invalid references.

Avoiding your Code Becoming Dependent on the Container