fusion-generator value fluid_input_graphics required by game

[ArkadiPorovozov]

I played around with the merge generator prototype and found that the Fluid_input_graphics value is required for the game to work.
here is the error:
Failed to load mods: Error while running setup for entity prototype "reactor-g" (fusion-generator): fluid_input_graphics record for north direction contains 0 values but 3 (same as amount of input fluid connections) were expected

[Bilka]

Thanks for the note, I expanded the description for 2.0.65.