don't close tab if there is unsaved buffer in it

config/nvim/lua/user/tabs.lua

@@ -3,6 +3,19 @@ local M = {
 }
 
 M.close_tab = function()
+  local wins = vim.api.nvim_tabpage_list_wins(0)
+
+  for _, win in ipairs(wins) do
+    local bufnr = vim.api.nvim_win_get_buf(win)
+    local is_modified = vim.api.nvim_buf_get_option(bufnr, "modified")
+
+    if is_modified then
+      local bufname = vim.fn.bufname(bufnr)
+      print(bufname .. " is not saved")
+      return
+    end
+  end
+
   table.insert(M.history, vim.fn.bufnr("%"))
   vim.cmd("tabclose")
 end