Suptertab chaining is not working with neovim LSP about supertab HOT 2 OPEN

+1 for this from me, same issue precisely. I might have a poke around in Supertab in the next week or two to try to figure out a fix.

Edit: I ended up switching to mucomplete, so I won't be looking any further on this.

from supertab.

This happens because SuperTabCodeComplete has the line:

let Func = function(b:SuperTabChain[0])

which makes a funcref out of b:SuperTabChain[0], and the docs for v:lua explicitly say:

Note: v:lua without a call is not allowed in a Vimscript expression: Funcrefs cannot represent Lua functions.

You can work around this with the following:

vim.cmd [[
  function! SuperTabLspOmnifunc(findstart, base)
    return v:lua.vim.lsp.omnifunc(a:findstart, a:base)
  endfunction
]]
vim.bo.omnifunc = "SuperTabLspOmnifunc"
-- Reactivate completion chaining after setting omnifunc (see `:h supertab-completionchaining`)
vim.fn.SuperTabChain("SuperTabLspOmnifunc", "<c-p>")
vim.fn.SuperTabSetDefaultCompletionType("<c-x><c-u>")

from supertab.