Virtual Scroller: Event first and last behave differently

[Mettbrot]

Describe the bug

In the virtual scroller event, first is counted zero based, while last is counted 1 based.

Pull Request Link

No response

Reason for not contributing a PR

• Lack of time
• Unsure how to implement the fix/feature
• Difficulty understanding the codebase
• Other

Other Reason

No response

Reproducer

https://stackblitz.com/edit/f5xvgjnv?file=src%2FApp.vue

Environment

Stackblitz Environment

Vue version

3.2.45

PrimeVue version

4.2.5

Node version

No response

Browser(s)

No response

Steps to reproduce the behavior

• In the beginning virtual scroller is at the top: first = 0, last = 8
• Scroll to the bottom
• first is 9994, last is 10000. But the latest item has the (zero based) number 9999

See this screenshot:

Expected behavior

The value of last in the event should also be counted zero based and should point to 9999 in the stackblitz example.

[Mettbrot]

The naming first and last suggests that the same counting method is used. If this is not the case (and this is not a bug), last should maybe be renamed to size or something.