Missing response and return handling in DrimageSubscriber image delivery

Problem/Motivation

The DrimageSubscriber::onKernelRequest() method does not properly set a response using $event->setResponse() when delivering generated images. Additionally, several error branches are missing return statements, which may allow execution to continue and cause unexpected behavior.

This can result in:

• Images not being delivered correctly
• Duplicate processing
• Unexpected fall-through logic
• Possible PHP warnings or broken responses
• Inconsistent kernel request handling

Steps to reproduce

1. Request a generated Drimage image.
2. Trigger a path handled by DrimageSubscriber.
3. Observe that response handling is incomplete.
4. Error branches continue execution without returning.
5. Image delivery may fail or behave inconsistently.

Proposed resolution

Update `DrimageSubscriber::onKernelRequest()` to:

• Call $event->setResponse($response) when an image response is generated
• Add missing return statements after setting responses
• Add return statements in error handling branches
• Ensure early exits when request is fully handled

This ensures proper Symfony event handling and prevents fall-through execution.

Remaining tasks

• ✅ File an issue
• ➖ Addition/Change/Update/Fix
• ➖ Testing to ensure no regression
• ➖ Automated unit testing coverage
• ➖ Automated functional testing coverage
• ➖ UX/UI designer responsibilities
• ➖ Readability
• ➖ Accessibility
• ➖ Performance
• ➖ Security
• ➖ Documentation
• ➖ Code review by maintainers
• ➖ Full testing and approval
• ➖ Credit contributors
• ➖ Review with the product owner
• ➖ Release notes snippet
• ❌ Release

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• N/A