Getting the values for the cells if there is 1 or more values assigned

How do I fix this if I have cells having values for 2 or more for SHEET1 in columns A & B with this code: (I don't have any problems)

Dim LineNumbers() As Variant
LineNumbers = Range("A1", ActiveSheet.Cells(Rows.Count, "A").End(xlUp))
Dim Lengths() As Variant
Lengths = Range("B1", ActiveSheet.Cells(Rows.Count, "B").End(xlUp))      

But if there is only 1 value for the row on columns A & B this raises an error. I read here that if I use usedrange, CountA and xldown is not recommended to get the last used row as it causes some errors for the results, then the code above is much efficient. Unfortunately for me when I have only 1 value in my LineNumbers and Lengths this raises an error.

Writing From a Range to an Array

Dim LineNumbers As Variant
Dim Lengths As Variant

With ActiveSheet
    With .Range("A1", .Cells(.Rows.Count, "A").End(xlUp))
        If .Rows.Count = 1 Then ' one cell
            ReDim LineNumbers(1 To 1, 1 To 1): LineNumbers(1, 1) = .Value
        Else ' multiple cells
            LineNumbers = .Value
        End If
    End With
    With .Range("B1", .Cells(.Rows.Count, "B").End(xlUp))
        If .Rows.Count = 1 Then ' one cell
            ReDim Lengths(1 To 1, 1 To 1): Lengths(1, 1) = .Value
        Else ' multiple cells
            Lengths = .Value
        End If
    End With
End With