keyboardlayout: Don't break if parsing the layout fails (#1154)

Fixes: https://github.com/awesomeWM/awesome/issues/1108
Signed-off-by: Uli Schlachter <psychon@znc.in>

lib/awful/widget/keyboardlayout.lua

@@ -10,6 +10,7 @@ local textbox = require("wibox.widget.textbox")
 local button = require("awful.button")
 local util = require("awful.util")
 local widget_base = require("wibox.widget.base")
+local gdebug = require("gears.debug")
 
 --- Keyboard Layout widget.
 -- awful.widget.keyboardlayout
@@ -233,8 +234,8 @@ local function update_layout(self)
     self._layout = {};
     local layouts = keyboardlayout.get_groups_from_group_names(awesome.xkb_get_group_names())
     if layouts == nil or layouts[1] == nil then
-        error("Failed to get list of keyboard groups")
-        return;
+        gdebug.print_error("Failed to get list of keyboard groups")
+        return
     end
     if #layouts == 1 then
         layouts[1].group_idx = 0