Navigate until there is no sheet left - vba

Question

I have a task for school. On my worksheet there is a button with next sheet and previous sheet. But I want that it always checks if possible to move to the next sheet.
For example, three sheets. I start on sheet 1 and click next. Then on sheet 2 I click next. I'm on sheet 3 and I click next, so a message box comes up "there are no sheets left." but if I add another sheet it needs to move on to sheet 4.
Here is the code that I already have:
If ActiveSheet.Index = Worksheets.Count Then
Worksheets(1).Select
Else
ActiveSheet.Previous.Select
End If

Answer 1

If ActiveSheet.Index <> Worksheets.Count Then
ActiveSheet.Next.Select
Else
MsgBox "There are no more sheets left."
End If

Answer 2

if you aim to simply add Command Button to every page then you would have to copy this code in each of the command buttons on all pages(design mode-doubleclick the command button)
Private Sub CommandButton1_Click()
Dim sheetnum As Integer
sheetnum = ActiveSheet.Index
If sheetnum = ThisWorkbook.Sheets.Count Then
ThisWorkbook.Sheets(1).Activate
MsgBox "You are at last sheet returning to the first sheet."
Else
ThisWorkbook.Sheets(sheetnum + 1).Activate
End If
End Sub
Or you would have to create a module and call function from command button.
Like this:
In CommandButton code on every page:
Call newpage
In Module1:
Public Sub newpage()
Dim sheetnum As Integer
sheetnum = ActiveSheet.Index
If sheetnum = ThisWorkbook.Sheets.Count Then
ThisWorkbook.Sheets(1).Activate
MsgBox "You are at last sheet returning to the first sheet."
Else
ThisWorkbook.Sheets(sheetnum + 1).Activate
End If
End Sub