[3/4] Refactor: init: Use async | Move theme stuff to theme.lua

third commit of refactor

perf improvements due to async

run packer sync if base16 not found

this is not perfect error handling for initial run, but something

handle require errors

lua/mappings.lua

@@ -76,7 +76,17 @@ _G.s_tab_complete = function()
 end
 
 function _G.completions()
-    local npairs = require("nvim-autopairs")
+    local npairs
+    if
+        not pcall(
+            function()
+                npairs = require "nvim-autopairs"
+            end
+        )
+     then
+        return
+    end
+
     if vim.fn.pumvisible() == 1 then
         if vim.fn.complete_info()["selected"] ~= -1 then
             return vim.fn["compe#confirm"]("<CR>")