update std doc

Author: actboy168

meta/template/basic.lua

@@ -83,8 +83,8 @@ function ipairs(t) end
 ---#DES 'load<5.1'
 ---@param func       function
 ---@param chunkname? string
----@return function
----@return string   error_message
+---@return function?
+---@return string?   error_message
 ---@nodiscard
 function load(func, chunkname) end
 ---#else
@@ -93,26 +93,26 @@ function load(func, chunkname) end
 ---@param chunkname? string
 ---@param mode?      loadmode
 ---@param env?       table
----@return function
----@return string   error_message
+---@return function?
+---@return string?   error_message
 ---@nodiscard
 function load(chunk, chunkname, mode, env) end
 ---#end
 
 ---#if VERSION <= 5.1 and not JIT then
 ---#DES 'loadfile'
 ---@param filename? string
----@return function
----@return string   error_message
+---@return function?
+---@return string?  error_message
 ---@nodiscard
 function loadfile(filename) end
 ---#else
 ---#DES 'loadfile'
 ---@param filename? string
 ---@param mode?     loadmode
 ---@param env?      table
----@return function
----@return string   error_message
+---@return function?
+---@return string?  error_message
 ---@nodiscard
 function loadfile(filename, mode, env) end
 ---#end
@@ -121,8 +121,8 @@ function loadfile(filename, mode, env) end
 ---#DES 'loadstring'
 ---@param text       string
 ---@param chunkname? string
----@return function
----@return string error_message
+---@return function?
+---@return string?   error_message
 ---@nodiscard
 function loadstring(text, chunkname) end
 

meta/template/os.lua

@@ -69,7 +69,7 @@ function os.exit(code, close) end
 
 ---#DES 'os.getenv'
 ---@param varname string
----@return string
+---@return string?
 ---@nodiscard
 function os.getenv(varname) end