Angular11Typeundefinedisnotassignabletotype'T'

I am trying to use this google dynamic form for Angular 11 as is and I get errors.

Here is all the code copied verbatim, obviously it works here but is giving me errors on my dev machine.
https://stackblitz.com/edit/angular-sccsnu?file=src%2Fapp%2Fquestion-base.ts

? Compiled successfully.

Error: src/app/_models/question-base.ts:21:5 - error TS2322: Type 'T | undefined' is not assignable to type 'T'.
  'T' could be instantiated with an arbitrary type which could be unrelated to 'T | undefined'.
    Type 'undefined' is not assignable to type 'T'.
      'T' could be instantiated with an arbitrary type which could be unrelated to 'undefined'.

21     this.value = options.value;
       ~~~~~~~~~~

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