Problem with neovim builtin LSP (NA in position)

I'm experiencing a problem while editing R package in neovim using the builtin LSP support.
It might be that it is not languageserver problem, but here is what led me to think that it might be a good idea to report it here:

Every few keystrokes I get the following message:

Error executing lua /usr/share/nvim/runtime/lua/vim/lsp/util.lua:165: attempt to compare number with string

which corresponds to the following code in util.lua:

--- Position is a https://microsoft.github.io/language-server-protocol/specifications/specification-current/#position
--- Returns a zero-indexed column, since set_lines() does the conversion to 1-indexed
local function get_line_byte_from_position(bufnr, position)
  ...
  local col = position.character
  -- When on the first character, we can ignore the difference between byte and
  -- character
  if col > 0 then  -- <- HERE is the problem
  ...

Concretely, in those cases col is a string "NA" which has led me to post it here.
A quick fix is to add if col == "NA" then return -1 end, which at least silents the message, but I was wondering if some code range could have been propagated wrongly.

Reproduce the error while editing an R package in Neovim and start at /usr/share/nvim/runtime/lua/vim/lsp/util.lua:165, where position.character is compared with a number. Trace which language-server response supplies the "NA" value and whether the range was propagated incorrectly. Done means the reported edit no longer triggers the error and the position data is handled consistently.