I am trying to create a type based on an abstract readonly string[] in an abstract class. When I do so, two things happen:

1. I get the error 'U' only refers to a type, but is being used as a value here.
2. The value passed to the column() allows for any type of string

Here is an example in the playground.

What I want to happen, is for the array of strings to be converted to a union type for the parameter of the column() method.

export abstract class Table {
  abstract fields: readonly string[];
}

export class MyTable extends Table {
  fields: readonly string[] = ['a', 'b', 'c'];
}

export class ResultSet<T, U extends Table> {
  protected readonly _rows: T[] | T;

  constructor(
    rows: T[] | T,
    readonly table: U,
  ) {
    this._rows = rows;
  }

  column(name: (typeof U['fields'][number])) {

  }
}


const set = new ResultSet([], new MyTable());
set.column('123'); // Should throw error