[BUG] Downloading csv report fails for different date format

[rupal-bq]

What is the bug?
Downloading csv report is returning error Cannot assign to read only property 'since' of object '#<Object>' when date format is not default.

How can one reproduce the bug?
Steps to reproduce the behavior:

1. Go to Advanced Settings
2. Change Date Format
3. Try downloading csv report with date field.
4. See error

What is the expected behavior?
CSV report should be downloaded

[pantinor]

I see similar but related issue where the datetime is not populated at all in the CSV.