Homepage appearing in the translation field when editing a deleted sentence

[Guybrush88]

To Reproduce
Steps to reproduce the behavior:

1. Translate a sentence
2. Open it on a new tab
3. Delete the sentence
4. Go to the previous tab and edit the sentence, confirming the editing
5. See that the field where you add the translation now shows the homepage of Tatoeba

Screenshots (if applicable)

Additional information (if relevant)

I'm using Windows 11 and Chrome 145.0.7632.117

Expected behaviour

An error message should appear.

[jiru]

Thank you. I can reproduce this bug, although it requires to:

• use the old design
• have corpus maintainer or admin role, because you need to be able to delete the translation you just added

Relevant code:

tatoeba2/src/Controller/SentencesController.php

Lines 352 to 353 in 8f23c3a

	// TODO Better error handling.
	$this->redirect(array('controller' => 'pages', 'action' => 'home'));

[kumakyoo42]

Maybe we could add an "old design" label for issues that only apply to the old design? These issues could then all be closed the moment the old design is removed. (I personally do not see a good reason to fix problems that only apply to the old design, especially if they are not very severe.)