File importer gives incorrect error message: says "received nil" but really it's a duplicate PK error

This is regarding the GUI "File Importer" feature on a database that allows you to drag-and-drop CSV files.

Upon importing a file with a duplicate primary key, the error message given is

`write failed processing due to: column received nil but is non-nullable`

The true error is that there is a duplicate PK in the CSV file.