Typescript expression can't follow value has been checked for undefined outside of it

See example below that even though I am checking if foundFoo is truthy, inside the function expression, it still sees it as possibly undefined

interface A {
    name: string,
    value: number
}

interface B {
    fk: number
}

let fooArray: Array<A> = [{name: 'a', value: 1}, {name: 'b', value: 2}];
let bazArray: Array<B> = [{fk: 1}, {fk: 2}];
let foundFoo = fooArray.find((entry) => entry.name === 'a');
if (foundFoo) {
    bazArray.filter((entry) => entry.fk === foundFoo.value); // foundFoo is marked as possibly undefined
    bazArray.forEach((entry) => entry.fk === foundFoo.value); // foundFoo is marked as possibly undefined
}