lspconfig.lua

    -- Change the Diagnostic symbols in the sign column (gutter)
    -- (not in youtube nvim video)
    local signs = { Error = "", Warn = "", Hint = "󰠠", Info = "" }
    for type, icon in pairs(signs) do
      local hl = "DiagnosticSign" .. type
      vim.fn.sign_define(hl, { text = icon .. " ", texthl = hl, numhl = "" })
    end

    -- Change the diagnostic symbols by the error message
    vim.diagnostic.config({
      virtual_text = {
        format = function(diagnostic)
          local icons = {
            [vim.diagnostic.severity.ERROR] = signs.Error,
            [vim.diagnostic.severity.WARN]  = signs.Warn,
            [vim.diagnostic.severity.INFO]  = signs.Info,
            [vim.diagnostic.severity.HINT]  = signs.Hint,
          }
          return string.format("%s %s", icons[diagnostic.severity], diagnostic.message)
        end,
        prefix = "",
        spacing = 2,
      },
      signs = true,
      update_in_insert = false,
    })