Is there a way to use PythonAPI loadRes and COCOeval with empty detections?

[tomikoskinen]

I am trying to run a simple evaluation:

    cocoGt = COCO(json_gt_path)
    cocoDt = cocoGt.loadRes(json_pr_path)
    cocoEval = COCOeval(cocoGt, cocoDt, "bbox")
    cocoEval.evaluate()
    cocoEval.accumulate()
    cocoEval.summarize()

, where my detector did not detect any box-annotations, so json_pr_path only has an empty array [].
This leads to an error in coco.loadRes:

pycocotools/coco.py", line 335, in loadRes if 'caption' in anns[0]: ~~~~^^^ IndexError: list index out of range

Is there a way to use these functions and evaluate with zero predicted/detected boxes?