bug(mat-select): on openedChange, the panel value is wrong

[jordandoan]

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

18.1.2

Description

When triggering the event "openedChange," the panel value is defined when the panel is closed (openedChange emits false) and the panel value is undefined when the panel is open (openedChange emits true).

A current workaround is setting your logic based around the panel in a setTimeout function. My use case for this is setting an event listener on the scroll for the panel.

Reproduction

StackBlitz link:
https://stackblitz.com/edit/brlpethk?file=src%2Fexample%2Fselect-custom-trigger-example.html
Steps to reproduce:

1. Open panel
2. See that the panel value is undefined
3. Close panel
4. See that the panel value is defined

Expected Behavior

When the panel opens, the panel value should be defined

Actual Behavior

The panel value is undefined

Environment

• Angular: 19.2.14
• CDK/Material: 19.2.18
• Browser(s): Firefox
• Operating System (e.g. Windows, macOS, Ubuntu): Mac 14.7.6

[crisbeto]

It's likely because of this Promise.resolve, but I suspect that there will be lots of breakages if we remove it https://github.com/angular/components/blob/main/src/material/select/select.ts#L775