I don't have a concrete misbehavior from it, but this update of
`insert_range` doesn't make sense for two reasons:

* If the resolved completion doesn't have a new `text_edit` it would
clear out the `insert_range`.

* It doesn't update the completion if it has already been resolved,
except this update of `insert_range` happened before that.

Guessing it was written this way because this field needed to only be
mutated within the `CompletionSource::Lsp` case and this was a
convenient match below.

Release Notes:

- N/A

Co-authored-by: Smit <smit@zed.dev>