Error in PolygonField validation

arkindex.project.serializer_fields.PolygonField is used in a nested field of bulk transcription serializers. When validating this field value, min_length do not seems to be used. With a polygon of one point, the error message is an empty string.

endpoint: https://preprod.arkindex.teklia.com/api/v1/element/09a1f0d2-48c4-41b0-84ed-6d3a2a97bfd6/transcriptions/bulk/
payload:

{
    "element_type": "line",
    "transcription_type": "line",
    "source": "tesseract",
    "transcriptions": [
        {
            "text": "sunny",
            "score": ".5",
            "polygon": [[1037, 1037]]
        }
    ]
}