i am trying to assign a string as an argument to give keys of my object as an argument to the method and i get this error

Question

Argument of type 'string' is not assignable to parameter of type 'keyof T'. Type 'string' is not assignable to type 'never'.

interface ModelAttributes<T extends object> {
  get<K extends keyof T>(key: K): T[K];
  set(update: T): void;
  getAll(): T;
}

fetch(): void {
    const id = this.get('id'); here where i get the error 
    if (typeof id !== 'number') {
      throw new Error('cannot fetch without an id');
    }