Fix string component containging ['{] taking long to load

lua/lualine/utils/loader.lua

@@ -1,8 +1,10 @@
 -- Copyright (c) 2020-2021 hoob3rt
 -- MIT license, see LICENSE for more details.
 local notice = require'lualine.utils.notices'
+local utils = require'lualine.utils.utils'
 
 local function lualine_load(patern, use_cache)
+  assert(utils.is_valid_filename(patern[#patern]), "Invalid filename")
   local retval, cache_name = nil, nil
   local sep = package.config:sub(1,1)
 

lua/lualine/utils/utils.lua

@@ -75,4 +75,9 @@ function M.is_focused()
   return tonumber(vim.g.actual_curwin) == vim.fn.win_getid()
 end
 
+function M.is_valid_filename(name)
+  local invalid_chars="[^a-zA-Z0-9_. ]"
+  return name:find(invalid_chars) == nil
+end
+
 return M