Today when I opened my game I got the following error:

"Failed to load mods: Error while loading entity prototype "osp_blink-projectile"(projectile): Key "type" not found in property tree at ROOT.projectile.osp_blink-projectile.action[0].action_delivery.target_effects Modifications: Spell Pack"

But yesterday I was playing normally without any issues with this mod on. I tried loading only this mod and the issue still persist. Does this have something to do with the last update of the game 0.18.21 ?

Yeah, I think it was 0.18.20 that broke it. I'm sure it'll be updated fairly soon though. It's usually updated within a week or so of a game update that breaks it.

fixed