The LLM editor dialog shows a raw translation key when its form fails to load

Problem

When the LLM assistant dialog of the CKEditor plugin cannot load its form (for example when the LLM application page is unreachable or returns an error), the error box shows the raw key llm.llm.editor.modal.failedToLoadForm instead of a message.

Cause

AI.Code.CKEditorPlugin asks the llm-translation loader for llm.editor.modal.failedToLoadForm, but that loader already prefixes every key with llm., so the key is looked up twice prefixed. The key is also missing from AI.Code.Translation and from the loader's key list, so even the correctly prefixed lookup had nothing to find.