@Hanna_Petruschat_WMDE There was some discussion around T212869, the check for label and description, today and it turns out this is actually not a check against other entities with the same combination of label and description as feared, but within our one entity, having a the same label and description in any given language - so something that would be perfect for in-form validation. A beauty of this is that we can - of course - detect this in real time without an API request. A change that we did for lexeme comes to mind - try here to add another lemma in language "de" and see what happens. Would that work for termbox?

/cc @Lea_WMDE I think this could be considered a dedicated feature story rather than generic error handling...

/cc @Lea_WMDE I think this could be considered a dedicated feature story rather than generic error handling...

Agreed. I started a stub: T222780: Disallow duplicate information in Termbox

Not sure if this is relevant here, but the most frequent unhappy paths I notice are:

• slow loading of page, clicking "edit" leads to the special page

• for lexemes, the gloss I like to type has more than 17 characters

Somehow I like the summary. Anyways, here it is for future reference

• Dropped network connection between page load and save
• Very slow / hanging save request
• Merge conflict with edit
• Permission denied: e.g. user banned / wikibase in read only mode
• Entity changed due to another user editing
• User edits a language that doesn't exist on Wikibase
• Redundant label and description (T212869)
• Equal label and description in a given language T222780
• When loading of the page is slow, clicking "edit" leads to the special page
• for lexemes, users tries to type a gloss that has more than 18 characters