useStyle: matching document.getElementById(id) when id is undefined could break css injection

[luca-peruzzo]

Describe the bug

In useStyle.ts there is this code:

styleRef = this.document.querySelector(`style[data-primeng-style-id="${name}"]`) || this.document.getElementById(id) || this.document.createElement('style');

when we have not already injected a specific css (for example inputotp-variables) id is undefined and this.document.getElementById(id) could match an element that has id="undefined" for example <span id="undefined">content</span> causing a style issue for missing css.
It is very uncommon (and ugly) to create an id with value "undefined" but this isn't forbidden by html rules.

Environment

Angular v18 webapp

Reproducer

https://stackblitz.com/edit/github-xypllzpu

Angular version

18.2.2

PrimeNG version

18.0.0

Build / Runtime

Angular CLI App

Language

TypeScript

Node version (for AoT issues node --version)

22.11.0

Browser(s)

No response

Steps to reproduce the behavior

1. Just run the stackblitz repo

Expected behavior

id="undefined" must not break style injection

[github-actions]

More information is needed to find a solution. A runnable StackBlitz example and additional details would be helpful.