type UnWrapValue<T> = T extends Array<infer TValue> ? TValue | null : never;

type UnWrapObject<T> = {
  [P in keyof T]: UnWrapValue<T[P]>;
};

interface DefaultProps {
  prop1: number[];
  prop2: string[];
}

interface ExtendedProps extends DefaultProps {
  prop3: boolean[];
}

class SuperKlass<T> {
  unwrapped!: UnWrapObject<T>;
  original!: T;
}

// It appears to me that the default generic type isn't being accounted for here.
// I would expect T to be at least DefaultProps and and be able to get that typing, however, it 
// is unable to infer the typing.
class SubKlass<T extends DefaultProps = DefaultProps> extends SuperKlass<T> {
  method1(){
    // Why does the typing NOT work here?
    this.unwrapped.prop1 = 1;
  }
}

class OneDeeper extends SubKlass<ExtendedProps> {
  method2(){
    // Why does the typing work here?
    this.unwrapped.prop1 = 1;
    this.unwrapped.prop3 = false;
  }
}