FIX more bugs

src/i_o.lua

@@ -57,7 +57,7 @@ local read_entire_file = function(file, regex, mode)
 	local str = file:read(mode or '*a')
 	file:close()
 	if not str then return end
-	if regex then return __string_match(str, regex) or '' else return str end
+	if regex then return __string_match(str, regex) else return str end
 end
 
 M.read_file = function(path, regex, mode)

src/modules/graphics.lua

@@ -15,7 +15,6 @@ return function(update_freq, config, common, width, point)
    -- nvidia state
 
    i_o.assert_exe_exists(NVIDIA_EXE)
-   i_o.assert_file_exists(config.dev_power)
 
    -- vars to process the nv settings glob
    --
@@ -52,7 +51,7 @@ return function(update_freq, config, common, width, point)
    local update_state = function()
       if i_o.read_file(config.dev_power, nil, '*l') == 'on' then
          local nvidia_settings_glob = i_o.execute_cmd(NV_QUERY)
-         if nvidia_settings_glob == '' then
+         if nvidia_settings_glob == nil then
             mod_state.error = 'Error'
          else
             mod_state.used_memory,