Typescript does not report an error with the sample

[Lonli-Lokli]

One more case when typescript does not report an error with the sample (link)

import {sample, createEvent, createStore} from "effector";

type AnyObject = {
    name: string;
}
function isDefined<T>(value: T | null | undefined): value is T {
    return  value !== null && value !== undefined;
}

const voidEvent = createEvent();
const stringEvent = createEvent<string>();
const $nullableStore = createStore<AnyObject | null>(null);

sample({
  clock: voidEvent,
  source: $nullableStore,
  filter: isDefined,
  target: stringEvent
});

Originally posted by @Lonli-Lokli in #811 (comment)

[zerobias]

Functions with generics are tough to generalize in typescript, so it’s very hard for us to make this working properly, but we’ll try

[Lonli-Lokli]

An example how it's done with RxJS

https://github.com/ReactiveX/rxjs/blob/master/src/internal/operators/filter.ts#L7

export function filter<T, S extends T, A>(predicate: (this: A, value: T, index: number) => value is S, thisArg: A): OperatorFunction<T, S>;
export function filter<T, S extends T>(predicate: (value: T, index: number) => value is S): OperatorFunction<T, S>;
export function filter<T>(predicate: BooleanConstructor): OperatorFunction<T, TruthyTypesOf<T>>;
/** @deprecated Use a closure instead of a `thisArg`. Signatures accepting a `thisArg` will be removed in v8. */
export function filter<T, A>(predicate: (this: A, value: T, index: number) => boolean, thisArg: A): MonoTypeOperatorFunction<T>;
export function filter<T>(predicate: (value: T, index: number) => boolean): MonoTypeOperatorFunction<T>;
export function filter<T>(predicate: (value: T, index: number) => boolean, thisArg?: any): MonoTypeOperatorFunction<T> {