Donut - DOC QA - Training the model to say "Answer not found"

@nielsr Hey there! Thanks for all the wonderful work that you do. I came across your doc vqa guide for tuning models like Donut. I was wondering whether the model can be tuned to say that the answer we are looking for was not found on the page rather than output random stuff. I was hoping you’d have some insight on this. Thanks for taking your time to read this and I can’t wait to hear back from you.