Copy empty Screentip from a Hyperlink goes to Invalid Procedure Call or Argument error

Sub Test()
    Dim a As String
    Dim b As String
    Dim c As String
    
    Range("A1").Hyperlinks.Add anchor:=Range("A1"), Address:="any address", TextToDisplay:="Link"
    
    a = Range("A1").Hyperlinks(1).Address
    b = Range("A1").Hyperlinks(1).screentip
    c = Range("A1").Hyperlinks(1).TextToDisplay

    If b = "" Then b = ""    'THIS IS THE SOLUTION. Without it the Hyperlinks.Add makes run-time error '5'
    
    Range("B1").Hyperlinks.Add anchor:=Range("B1"), Address:=a, screentip:=b, TextToDisplay:=c
End Sub