beginning of document word and vba

In my code i am selecting all the text around where text is selected, that is underlined.
However if the text is at the very start of the document it throws an error,
what code would i need to insert so that it does this unless/untill it hits the start of the document??

Here's my code:

Dim lClr As Long
Dim rTmp As Range

Set rTmp = Selection.Range
lClr = Selection.Font.UnderlineColor

Do While rTmp.Previous.Font.UnderlineColor = lClr
rTmp.start = rTmp.start - 1
Loop

Do While rTmp.Next.Font.UnderlineColor = lClr
rTmp.End = rTmp.End + 1
Loop

The .Previous with no where to go is the issue. If you use the Words collection and test if your on the
first word then you can avoid the error.

VB Code:

If rTmp.Words(1).Start > 1 Then '...