fix tests

button.lua

@@ -9,6 +9,9 @@
 
 -- draw button and queue up event handlers
 function button(State, name, params)
+  if State.button_handlers == nil then
+    State.button_handlers = {}
+  end
   if params.bg then
     love.graphics.setColor(params.bg.r, params.bg.g, params.bg.b, params.bg.a)
     love.graphics.rectangle('fill', params.x,params.y, params.w,params.h, 5,5)
@@ -19,6 +22,9 @@ end
 
 -- process button event handlers
 function mouse_press_consumed_by_any_button(State, x, y, mouse_button)
+  if State.button_handlers == nil then
+    return
+  end
   local button_pressed = false
   local consume_press = true
   for _,ev in ipairs(State.button_handlers) do