public Feature pointAlongLine(String layer, double ratio) {
    try {
      return geometry(layer, source.pointAlongLine(ratio));
    } catch (GeometryException e) {
      e.log(stats, "feature_point_along_line", "Error getting point along line for " + source);
      return empty(layer);
    }
  }
Starts building a new point map feature at a certain ratio along the linestring or longest segment if it is a
multilinestring.

@param layer the output vector tile layer this feature will be written to
@param ratio the ratio along the line: 0 for start, 1 for end, 0.5 for midpoint
@return a feature that can be configured further.
planetiler-core/src/main/java/com/onthegomap/planetiler/FeatureCollector.java