Angular D3 tree does not collapse back into its parent

We were able to use this example for Angular here(https://bl.ocks.org/d3noob/1a96af738c89b88723eb63456beb6510) and achieve the collapsible tree diagram. But it's not collapse back into its parent or our click action is not working properly.

Here is my code: https://stackblitz.com/edit/angular-ivy-acd2yd?file=src/app/app.component.ts

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