bug(aria/combobox): ComboboxPopup throws NG0950 when destroyed before its first change detection #33972

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

No response

Description

ComboboxPopup.ngOnDestroy calls this.combobox()._unregisterPopup(). The combobox input is input.required(). If the view that holds the popup is destroyed before its first update pass, the input was never set, and reading it throws NG0950: Input "combobox" is required but no value is available yet. Angular reports this as "Error during cleanup of component", and in tests it fails the test ("1 fixture threw errors during cleanup").

This happens in any unit test that creates a component containing a combobox and does not run change detection before teardown, for example a plain "should create" test, or a test that only checks providers.

Reproduction

import { Component } from '@angular/core';
import { TestBed } from '@angular/core/testing';
import { Combobox, ComboboxPopup, ComboboxWidget } from '@angular/aria/combobox';
import { Listbox, Option } from '@angular/aria/listbox';

@Component({
  imports: [Combobox, ComboboxPopup, ComboboxWidget, Listbox, Option],
  template: `
    <div ngCombobox #combobox="ngCombobox" tabindex="0">Pick one</div>
    <ng-template ngComboboxPopup [combobox]="combobox">
      <div ngListbox ngComboboxWidget #listbox="ngListbox" focusMode="activedescendant"
        [activeDescendant]="listbox.activeDescendant()">
        <div ngOption value="alpha" label="alpha">alpha</div>
      </div>
    </ng-template>
  `,
})
class Repro {}

it('destroys cleanly before the first change detection', () => {
  const fixture = TestBed.createComponent(Repro);
  expect(() => fixture.destroy()).not.toThrow();   // throws NG0950
});

Expected Behavior

Destroying the popup without a first change detection does nothing (there is nothing to unregister).

Actual Behavior

NG0950: Input "combobox" is required but no value is available yet, from ComboboxPopup.ngOnDestroy (src/aria/combobox/combobox-popup.ts, line 67 on main).

A possible fix: register in ngOnInit and keep the registered combobox in a field, then unregister that field (if set) in ngOnDestroy, instead of reading the input again.

Workaround: wrap the ng-template ngComboboxPopup in @if (combobox) { … }, so the popup is only created in an update pass.

Environment

• Angular: 22.2.1
• CDK/Material: @angular/cdk 22.2.3, @angular/aria 22.2.3 (also in 22.3.0-next.2 and main)
• Browser(s): any (seen in Vitest with happy-dom)
• Operating System (e.g. Windows, macOS, Ubuntu): macOS