running current versions and keep running into this issue if i attempt to use it.

Failed to load mods: Cannot Copy, invalid prototype
stack traceback:
[C]: in function 'error'
kry_stdlib/stdlib/data/data.lua:194: in function 'copy'
mini-machines/func.lua:447: in function 'miniaturize'
mini-machines/data-final-fixes.lua:76: in main chunk

Hm, I'm not getting the error at default settings with a mostly vanilla modlist. Do you have any non-default settings for either mini or micro machines?

The line in the error references the vanilla electric furnace, do you have any mods that might affect furnaces?

it does not play with AAI industries.

That's odd, I'm not getting this error when running AAI Industry (v0.6.4) and Micro Machines (v3.0.1), with no other mods. It loads with or without Space Age, with or without Mini Machines. Are there any other mods that might be affecting furnaces, or any non-default settings you might be using?

ill list the mods im running, but when i turned off AAI industries it worked.

what i have is factory leveling, extended vanilla processing and advanced furnaces.

I was able to reproduce the error with just Extended Vanilla and Micro Machines; caused by their changing the internal machine type from "furnace" to "assembling machine", which is supposed to prevent accidentally smelting coal into one of their new products, by forcing the user to set the recipe.

However, I don't believe they need to modify the electric furnace in this way, because those don't accept coal as fuel, so that issue would never occur with them. Can't upgrade from stone/steel furnace to electric furnace either, so yeah, just seems unnecessary to me; I don't like modifying vanilla machines for no reason.

BUT I know other mods have done this in the past (Krastorio 2 comes to mind), so I just changed the logic to be able to handle electric furnace whether it's internally considered a furnace or assembling machine. Should be fixed as of v3.0.2