fix(loader): check pack exists before apply color (#207)

Author: linrongbin16

lua/colorbox/loader.lua

@@ -1,6 +1,7 @@
 local logging = require("colorbox.commons.logging")
 local strings = require("colorbox.commons.strings")
 local tables = require("colorbox.commons.tables")
+local uv = require("colorbox.commons.uv")
 
 local configs = require("colorbox.configs")
 
@@ -17,6 +18,10 @@ M.load = function(colorname)
   if tables.tbl_empty(spec) then
     return
   end
+  local pack_exist = uv.fs_stat(spec.full_pack_path) ~= nil
+  if not pack_exist then
+    return
+  end
 
   local autoload_path = string.format("%s/autoload", spec.full_pack_path)
   vim.opt.runtimepath:append(autoload_path)