Return null when \Drupal::service() is called for non-existent service

I don't think we can do this without breaking existing code that expects to catch the exception.

Ideally you should avoid \Drupal::service() and use dependency injection instead.

One possible option is add a second argument to \Drupal::service() that passes through the second $invalid_behavior argument to the container, so you could do

\Drupal::service('non-existent-service', ContainerInterface::NULL_ON_INVALID_REFERENCE);

I am encountering this issue in hook_preprocess_HOOK(), so dependency injection is not possible. I'm using this to adjust the behaviour of the code based on whether or not another module is installed.

Is catching the exception better than just using \Drupal::hasService()?

I like the idea of adding a second param.

Preprocess functions can be OOP and use DI since 11.2! https://www.drupal.org/node/3496491 →

I think catching the exception is fine if it makes the code easier to read.

Due to module support, it will be a while before we can move to Drupal 11.

Option 1:

$service = \Drupal::hasService('service') ? \Drupal::service('service') : NULL;

Option 2:

try {
  $service = \Drupal::service('service');
}
catch (ServiceNotFoundException) {
  $service = NULL;
}

Option 1 is more compact.

I would rather just do:

$service = \Drupal::service('service');

Or:

$service = \Drupal::service('service', ContainerInterface::NULL_ON_INVALID_REFERENCE);

(The code later, in a loop, tests if $service has a value and uses the service if it does.)