userform textbox to function if kept blank - excel

Question

I have created a useform which helps me to change the column width and row height of active sheet or all the sheets (based on the selection option in Frame3) from column B or Column C (based on the selection option in Frame2) based on the text entered in the textbox1 and textbox2.
I have attacahed userform for your reference.
This code is working fine, however if I only need to change the column width not the row height then when I key in the column width and leave the row height empty then its giving me error on the below mentioned line:
Selection.Cells.RowHeight = Me.TextBox2.Value
Please let me know how should I modify my code that even if any of the textbox value is left blank (i.e if I only want to change the column width and maintain the row height as-is) then it should not give me error.
Userform Code:
Dim exworkb As Workbook
Dim xlwksht As Worksheet
Dim lastrow1 As Long
Dim lastcolumn1 As Long
Dim firstrowDB As Long
Dim Z As Integer
Dim ShtNames() As String
Private Sub CommandButton1_Click()
If Me.OptionButton3.Value = True Then
If Me.OptionButton1.Value = True Then
Call rowcolactivesheetb
Selection.Cells.RowHeight = Me.TextBox2.Value
Selection.Cells.ColumnWidth = Me.TextBox1.Value
ElseIf Me.OptionButton2.Value = True Then
ReDim ShtNames(1 To ActiveWorkbook.Sheets.Count)
For Z = 1 To Sheets.Count
ShtNames(Z) = Sheets(Z).Name
If ShtNames(Z) <> "Trans_Letter" And ShtNames(Z) <> "Cover" And ShtNames(Z) <> "Abbreviations" And InStr(ShtNames(Z), "_Index") = 0 Then
Sheets(Z).Select
lastrow1 = Sheets(Z).Cells(Rows.Count, "A").End(xlUp).Row
lastcolumn1 = Sheets(Z).Cells(1, Columns.Count).End(xlToLeft).Column
ActiveWorkbook.Sheets(Z).Range(Sheets(Z).Cells(1, 2), Sheets(Z).Cells(lastrow1, lastcolumn1)).Select
Selection.Cells.RowHeight = Me.TextBox2.Value
Selection.Cells.ColumnWidth = Me.TextBox1.Value
End If
Next Z
End If
End If
If Me.OptionButton4.Value = True Then
If Me.OptionButton1.Value = True Then
Call rowcolactivesheetc
Selection.Cells.RowHeight = Me.TextBox2.Value
Selection.Cells.ColumnWidth = Me.TextBox1.Value
ElseIf Me.OptionButton2.Value = True Then
ReDim ShtNames(1 To ActiveWorkbook.Sheets.Count)
For Z = 1 To Sheets.Count
ShtNames(Z) = Sheets(Z).Name
Sheets(Z).Select
If ShtNames(Z) <> "Trans_Letter" And ShtNames(Z) <> "Cover" And ShtNames(Z) <> "Abbreviations" And InStr(ShtNames(Z), "_Index") = 0 Then
lastrow1 = Sheets(Z).Cells(Rows.Count, "A").End(xlUp).Row
lastcolumn1 = Sheets(Z).Cells(1, Columns.Count).End(xlToLeft).Column
ActiveWorkbook.Sheets(Z).Range(Sheets(Z).Cells(1, 3), Sheets(Z).Cells(lastrow1, lastcolumn1)).Select
Selection.Cells.RowHeight = Me.TextBox2.Value
Selection.Cells.ColumnWidth = Me.TextBox1.Value
End If
Next Z
End If
End If
End Sub
Private Sub CommandButton2_Click()
Unload Me
End Sub
Module code:
Sub rowcolactivesheetb()
Dim exworkb As Workbook
Dim xlwksht As Worksheet
Dim lastrow1 As Long
Dim lastcolumn1 As Long
Dim firstrowDB As Long
With ActiveSheet
lastrow1 = .Cells(Rows.Count, "A").End(xlUp).Row
lastcolumn1 = .Cells(1, Columns.Count).End(xlToLeft).Column
.Range(.Cells(1, 2), .Cells(lastrow1, lastcolumn1)).Select
End With
End Sub
Sub rowcolactivesheetc()
Dim exworkb As Workbook
Dim xlwksht As Worksheet
Dim lastrow1 As Long
Dim lastcolumn1 As Long
Dim firstrowDB As Long
With ActiveSheet
lastrow1 = .Cells(Rows.Count, "A").End(xlUp).Row
lastcolumn1 = .Cells(1, Columns.Count).End(xlToLeft).Column
.Range(.Cells(1, 3), .Cells(lastrow1, lastcolumn1)).Select
End With
End Sub