Excel vba conversion to Librecalc

[Redrabbit]

I am trying to convert my Excel VBA macro for finding next free cell into Librecalc but It gives an error " unknow data type range".
>>> use code-tags <<<

Sub LastRow()
    Dim rngLast As Range

    With ThisWorkbook.Worksheets("Sheet1")
        If .Range("A1").Value = "" Then
            Set rngLast = .Range("A1")
        Else
            Set rngLast = .Cells(.Rows.Count, "A").End(xlUp).Offset(1, 0)
        End If
        MsgBox "Next blank row is " & rngLast.Address
    End With

End Sub

I would be grateful for help on the conversion please.
Regards John

 

[vletm]

Redrabbit​

If test only Your above code then
... for me,
it runs as smooth as possible
without any errors.

Do You have there something else?
... or what would be ... Librecalc?