Many years ago was I right to find a way to avoid a character using all his Karma for causing the death of A Npc when the Npc that died only died because I as The GM forgot to give the character information that would have guaranteed that The Npc didn't die?

Here's more info

Many years ago A player in A Marvel Campaign I was running caused the death of A Npc but it was my fault before I forgot to tell the player that the npc had a very severe nut allergy and because I'd forgot to tell him his character made the Npc a meal that contained nuts, which proved fatal

Luckily the players character was A Sorcerer and because it was my fault for forgetting to tell the player that the npc had a very severe nut allergy and because I'd forgot to tell him his character made the Npc a meal that contained nuts, which proved fatal I decided to avoid the character losing all his Karma, by using the fact that his character was A Sorcerer to change it so that what happened actually happened in a vision of the future, which allowed the player and his character to avoid causing the death

On the subject of the amount of Karma The Pc had he had something like 1,900 odd in A Advancement Pool that he was planning to use to get a new power and something like 500 Karma available for use

Wouldn't it have been simpler to simply handle it like you would in reality where the NPC, knowing that they had a severe allergy, carried an epipen and the PCs used it to save the NPC's life?

Why did this require magic, and a retcon, and all the other stuff when we could have handled this in real life with no magic or super powers?