Problem:
After eaacdc9, complete with emmylua_ls error with:
runtime/lua/vim/lsp/completion.lua:586: attempt to get length of field
'items' (a nil value)
Solution:
Result can be CompletionItem[] according the spec:
> If a `CompletionItem[]` is provided, it is interpreted to be complete,
> so it is the same as `{ isIncomplete: false, items }`
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