fix drop component

res/content/base/scripts/components/drop.lua

@@ -64,8 +64,12 @@ function on_sensor_enter(index, oid)
             local odrop = other:get_component("base:drop").dropitem
             if odrop.id == dropitem.id and not odrop.data then
                 local stack = item.stack_size(dropitem.id)
-                local sum = dropitem.count + odrop.count
-                if sum <= stack then
+                local sum = (dropitem.count or 0) + (odrop.count or 0)
+                if sum == 0 then
+                    dropitem:despawn();
+                    odrop:despawn();
+                    return
+                elseif sum <= stack then
                     dropitem.count = 0
                     odrop.count = sum
                     entity:despawn()