Fix bug when passing a date

[DarkSorrow]

I think there is a typo when the date has to be converted, it's the v that should be used and not the cell.v as it doesn't exist yet

Type:

The following has been addressed in the PR:

• There is a related issue?
• Unit or Functional tests are included in the PR

Description:

[silent-developer-shubham]

How to add the style in the header?

[DarkSorrow]

The function doesn't allow you to pass style. It needs to be done differently but i'm not working on that at the moment, i just helped a friend fix his code crashing because of that.
If i get some more time i'll try to take a look later but this fix will prevent a crash from the underlying library

[sujitdev]

Hi I am using this package. I am stuck in one point where I need to export the file in CSV format but if we pass file extension props as CSV. Then will download the file with CSV extension but the newly downloaded file is completely blank. No data into this File.Can any one is having example for this to download the file with CSV file extension