Configure Omnisharp in Neovim

Question

I am using lsp_zero to configure my lsp servers i am stuck with Omnisharp. i have this configuration file:

local lsp = require('lsp-zero').preset({})

lsp.on_attach(function(client, bufnr)
  lsp.default_keymaps({buffer = bufnr})
end)

lsp.ensure_installed({
    'rust_analyzer',
    'tsserver',
    'eslint',
    'lua_ls'
})

local lsp_config= require("lspconfig")

lsp_config.lua_ls.setup(lsp.nvim_lua_ls())

lsp_config['omnisharp'].setup {
    handlers = {
    ["textDocument/definition"] = require('omnisharp_extended').handler,
  },
    cmd = { '/usr/bin/OmniSharp', '--languageserver' }
}

lsp.setup()

When i open a cs file it loads the LSP server but i got this prompt each time i go to insert mode and it keeps showing up each time i press a key:

This is how i load my LSP-related plugins (i use Lazy.nvim):

    {
        'VonHeikemen/lsp-zero.nvim',
        branch = 'v2.x',
        dependencies = {
            -- LSP Support
            {'neovim/nvim-lspconfig'},             -- Required
            {                                      -- Optional
            'williamboman/mason.nvim',
            build = function()
                pcall(vim.cmd, 'MasonUpdate')
            end,
            },
            {'williamboman/mason-lspconfig.nvim'}, -- Optional

            -- Autocompletion
            {'hrsh7th/nvim-cmp'},     -- Required
            {'hrsh7th/cmp-nvim-lsp'}, -- Required
            {'L3MON4D3/LuaSnip'},     -- Required
        }
    },
    {
        'Hoffs/omnisharp-extended-lsp.nvim'
    }