stack recipes are now defaulting to cost 1 instead of null (#6640)

code/datums/recipe/stack_recipe.dm

@@ -8,7 +8,7 @@
  *
  * why? because this is easier to regex later if it turns out silicons code design(tm) was terrible
  */
-/proc/create_stack_recipe_datum(name, product, cost, amount = 1, sanity_checks = TRUE, time = 0, recipe_type = /datum/stack_recipe, category, exclusitivity, list/recipe_args)
+/proc/create_stack_recipe_datum(name, product, cost = 1, amount = 1, sanity_checks = TRUE, time = 0, recipe_type = /datum/stack_recipe, category, exclusitivity, list/recipe_args)
  // check this isn't being misused
  ASSERT(!ispath(recipe_type, /datum/stack_recipe/material))
  var/datum/stack_recipe/creating = isnull(recipe_args)? (new recipe_type) : (new recipe_type(arglist(recipe_args)))