The higher tiers of the research are not locked by the research for required science-packs.
Please add them to the prerequisite-attribute.
worker-robot-battery-4:
prerequisites = {"worker-robot-battery-1","production-science-pack"},
worker-robot-battery-8:
prerequisites = {"worker-robot-battery-4","utility-science-pack"},
worker-robot-battery-12:
prerequisites = {"worker-robot-battery-8","space-science-pack"},
