bat: added a handler for incompetent users

A lot of people expect widgets like this one to auto-magically work,
and somehow don't understand that *they* need to make sure there is a
source of information. Is ACPI module loaded? Is battery info exposed
in the same place that widget expects by default? You need to answer
those questions before loading the widget and sending me "bug"
reports.

bat.lua

@@ -32,10 +32,12 @@ local function worker(format, batid)
 
     -- Get /proc/acpi/battery info
     local f = io.open("/proc/acpi/battery/"..batid.."/info")
+    -- Handler for incompetent users
+    if not f then return {"/", "/", "/"} end
     local infofile = f:read("*all")
     f:close()
 
-    -- Check if the file wasn't found or the battery isn't present
+    -- Check if the battery is present
     if infofile == nil or string.find(infofile, "present:[%s]+no") then
         return {"/", "/", "/"}
     end

thermal.lua

@@ -17,8 +17,7 @@ module("vicious.thermal")
 local function worker(format, thermal_zone)
     -- Get an ACPI thermal zone
     local f = io.open("/proc/acpi/thermal_zone/" .. thermal_zone .. "/temperature")
-    -- Fix your ACPI setup, or find another source of temperature
-    -- exposed trough /sys, if a thermal_zone can't be found
+    -- Handler for incompetent users
     if not f then return {"N/A"} end
     local line = f:read("*line")
     f:close()