don't return degenerate geometries in fast intersects operation

when a geometry only touches the clipping polygon (and has no points inside the poly), `intersector.intersection()` will produce a "degenerate" version of the original geometry: a (multi)linestring when the geometry was a polygon, or a (multi)point when the geometry was a linestring.
This can lead to inconsistencies when a geometry-type filter is used (e.g. `geometry: polygon`), as the output will then potentially also contain geometries that don't match the filter.

Fixes GIScience/ohsome-api#339

oshdb-util/src/main/java/org/heigit/ohsome/oshdb/util/geometry/fip/FastPolygonOperations.java

@@ -184,10 +184,15 @@ public Geometry intersection(Geometry other) {
     }
 
     assert intersector != null;
+
+    Geometry result;
     if (other instanceof GeometryCollection) {
-      return other.intersection(intersector);
+      result = other.intersection(intersector);
     } else {
-      return intersector.intersection(other);
+      result = intersector.intersection(other);
+    }
+    if (result.getDimension() != other.getDimension()) {
+      return gf.createEmpty(other.getDimension());
     }
   }
 }