internal server error for density indicator

[Gigaszi]

Currently, the density indicator returns a 500 internal server error for the following request:

curl -X 'POST' \
  'https://api.quality.ohsome.org/v1/indicators/density' \
  -H 'accept: application/json' \
  -H 'Content-Type: application/json' \
  -d '{
  "bpolys": {
    "type": "FeatureCollection",
    "features": [
      {
        "geometry": {
          "coordinates": [
            [
              [
                8.674092292785645,
                49.40427147224242
              ],
              [
                8.695850372314453,
                49.40427147224242
              ],
              [
                8.695850372314453,
                49.415552187316095
              ],
              [
                8.674092292785645,
                49.415552187316095
              ],
              [
                8.674092292785645,
                49.40427147224242
              ]
            ]
          ],
          "type": "Polygon"
        },
        "properties": {},
        "type": "Feature"
      }
    ]
  },
  "topic": "poi",
  "includeFigure": true
}'