Log a proper warning when an unexected translation key is added to client side translations

[sgiehl]

Description:

In case a translation key is added to the client side translations that does not contain a _ a warning is currently triggered:

WARNING CoreHome[2024-12-13 12:02:09 UTC] [12316] /var/www/html/core/Translation/Translator.php(202): Warning - Undefined array key 1 - Matomo 5.2.0 - Please report this message in the Matomo forums: https://forum.matomo.org (please do a search first as it might have been reported already) #0/core/Translation/Translator.php(202),#1/core/AssetManager.php(147),#2/core/Twig.php(231),#3/tmp/templates_c/9b/9bcdbc324b7372161ba12b6ad9eb6285.php(43),#4/vendor/twig/twig/src/Template.php(360),#5/tmp/templates_c/b3/b35accd563c963c7f8a6fbee91f567bb.php(137),#6/vendor/twig/twig/src/Template.php(430),#7/vendor/twig/twig/src/Template.php(492),#8/tmp/templates_c/f9/f91be83f44d125f542a7d6c7c5b11fc0.php(68),#9/vendor/twig/twig/src/Template.php(430)

That does not really help a plugin developer to see where the problem is. This PR will discard such unexpected translations key and trigger a helpful warning instead.

refs #22853

Review

• Functional review done
• Potential edge cases thought about (behavior of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
• Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• Security review done
• Wording review done
• Code review done
• Tests were added if useful/possible
• Reviewed for breaking changes
• Developer changelog updated if needed
• Documentation added if needed
• Existing documentation updated if needed