How to stop error when I cancel the input file source command?

Hello,

I am using the following code to transfer battery testing data from .csv files into a .xlsm file.

It gets what I need done but, if I select "Cancel" from the input file box it creates a Run-time error '1004': 'False.xlsx' could not be found.........

What do I need to add to my code to stop this?

Sub CommandButton1_Click()

Dim batteryBook As Workbook
Dim filter As String
Dim caption As String
Dim batteryFilename As String
Dim batteryWorkbook As Workbook
Dim targetWorkbook As Workbook

Set targetWorkbook = Application.ActiveWorkbook


filter = "Text files (*.csv),*.csv"
caption = "Please Select an input file "
batteryFilename = Application.GetOpenFilename(filter, , caption)

Set batteryWorkbook = Application.Workbooks.Open(batteryFilename)


Dim targetSheet As Worksheet
Set targetSheet = targetWorkbook.Worksheets(1)
Dim sourceSheet As Worksheet
Set sourceSheet = batteryWorkbook.Worksheets(1)

targetSheet.Range("A1").Value = sourceSheet.Range("B1").Value   'Will be adding more ranges..


batteryWorkbook.Close

End Sub