in src/utils/nonNull.ts [8:14]
export function nonNullProp<TSource, TKey extends keyof TSource>(
source: TSource,
name: TKey
): NonNullable<TSource[TKey]> {
const value: NonNullable<TSource[TKey]> = <NonNullable<TSource[TKey]>>source[name];
return nonNullValue(value, <string>name);
}