Issue with using mapped types inside map

I've tried to make a mapped type where I used set of Enums for keys and functions as values but I'm failing to get exact type when using that object.

View this as a very simplified version of my problem, I know I could make this work with if/else or switch statement but because of performance and clarity I wish to use sort of an dictionary as a data structure.

enum PossibleOperationEnum {
    MULTIPLY = 'MULTIPLY',
    LENGTH = 'LENGTH',
}

 type MultiplyOperation = {
    operation: PossibleOperationEnum.MULTIPLY;
    element: number;
};

 type StringLengthOperation = {
    operation: PossibleOperationEnum.LENGTH;
    element: string;
};

type AllOperations = MultiplyOperation | StringLengthOperation;

type ModificationFunction<T> = (
    modification: Extract<AllOperations, { operation: T }>,
) => any;

// Simplified version (in the original I have a lot more keys/functions)
const config: { [k in PossibleOperationEnum]: ModificationFunction<k> } = {
    LENGTH: (mod) => mod.element.length,
    MULTIPLY: (mod) => mod.element * 2
};

const content: AllOperations[] = [
    {
        operation: PossibleOperationEnum.MULTIPLY,
        element: 1,
    },
    {
        operation: PossibleOperationEnum.LENGTH,
        element: "test"
    },
]


const contentList = content.map((mod) => {
    return config[mod.operation](mod); // this is evaluating to never even tho this code works perfectly fine in practice.
})

Also typescript playground link: Playground