failed to load mods: nucular-engineering/prototypes/entity.lua:99: attempt to index field 'action' (a nil value)
stack traceback:
nucular-engineering/prototypes/entity.lua:99: in main chunk
[C]: in function 'require'
nucular-engineering/data.lua:5: in main chunk

Mods to be disabled:
• nucular-engineering (1.2.7)

The atomic rocket prototype seems to have changed, so now the nuclear artillery shell copying from it errors out.
Until I get around to fixing this, probably within a week, it can be patched by unzipping the mod and editing the prototypes/entity.lua file. Comment out line 98-121 with a multi-line comment.
It should look like this after you're done:

--visuals
--[[effect = util.table.deepcopy(data.raw.projectile['atomic-rocket'].action.action_delivery.target_effects[14])
(... code ...)
effect.action.repeat_count = 1000 * 32
--]]
table.insert(atomic_shell.action.action_delivery.target_effects, effect)

This makes the nuclear artillery somewhat of a dud, so I don't want to push that change on everyone who might still run older versions of the game.

awesome thank you! for the quick fix just happy for it to be running

Should work out of the box now