fix(awful: widget: only_on_screen): update for screen API changes from #2293 (#2304)

lib/awful/widget/only_on_screen.lua

@@ -25,10 +25,12 @@ local function should_display_on(self, s)
     if not self._private.widget then
         return false
     end
-    local success, own_s = pcall(function()
-        return capi.screen[self._private.screen]
-    end)
-    return success and own_s == s
+    local own_s = self._private.screen
+    if type(own_s) == "number" and (own_s < 1 or own_s > capi.screen.count()) then
+        -- Invalid screen number
+        return false
+    end
+    return capi.screen[self._private.screen] == s
 end
 
 -- Layout this layout

tests/examples/shims/screen.lua

@@ -2,7 +2,9 @@ local gears_obj = require("gears.object")
 
 local screen, meta = awesome._shim_fake_class()
 
-screen.count = 1
+function screen.count()
+    return 1
+end
 
 local function create_screen(args)
     local s = gears_obj()