Calendar: Error on tab keydown

[Xylios13]

Describe the bug

Pressing tab several times in a p-calendar that is only showing time and is inline will lead to the following error:

preview-afd2289b8907a.js:2 ERROR TypeError: Cannot read properties of null (reading 'children')
    at Calendar.onContainerButtonKeydown (calendar.ts:2018:14)
    at Calendar_div_3_div_5_Template_button_keydown_8_listener (ɵcmp.js:268:29)
    at executeListenerWithErrorHandling (projection.ts:20:1)
    at wrapListenerIn_markDirtyAndPreventDefault (projection.ts:51:1)
    at HTMLButtonElement.eval (dom_renderer.ts:375:10)
    at _ZoneDelegate.invokeTask (zone.umd.js:446:35)
    at eval (ng_zone.ts:22:1)
    at AsyncStackTaggingZoneSpec.onInvokeTask (ng_zone.ts:22:1)
    at _ZoneDelegate.invokeTask (zone.umd.js:445:40)
    at Object.onInvokeTask (ng_zone.ts:442:22)

Environment

I was able to reproduce this error on a stackblitz, https://stackblitz.com/edit/github-naqavf?file=src%2Fapp%2Fapp.component.html

Reproducer

https://stackblitz.com/edit/github-naqavf?file=src%2Fapp%2Fapp.component.html

Angular version

17.3.4

PrimeNG version

17.13.0

Build / Runtime

Angular CLI App

Language

TypeScript

Node version (for AoT issues node --version)

18.19.0

Browser(s)

Chrome 123.0.6312.123

Steps to reproduce the behavior

1. Create a p-calendar with the following properties:

<p-calendar
  [inline]="true"
  [showTime]="true"
  [showSeconds]="true"
  [timeOnly]="true"
></p-calendar>

2. Give the focus to the calendar component (for example, select the hour display)
3. Press tab until you see a console error.

Expected behavior

It is expected that the tab key press works without any console error.