Hello @dscreve,
You seem to be using agent node-js package.
If this is indeed the case, you will find the doc for the file picker widget here, along with a in-depth example:
Please let me know if this would help you out.
Regards,
context.formValues['PDF Files'] is indeed not a native javascript/typescript File type object, but as shown at the top of the example its type is imported from @forestadmin/datasource-toolkit
import { File } from '@forestadmin/datasource-toolkit';
therefore it doesn’t expose arrayBuffer() method directly, but a buffer property