Fixed condition to no longer raise an error

The function that tries to deduce the classification of pure water or land tiles from imported geometries would throw an error (by definition) when the geometry consists of multiple parts that all resolve to the same quadkey.

This MR changes the ValueError to a warning and adds a check to not add the same quadkey twice.

\approve @ds @laurens

discretizer/quadtile.py

@@ -593,18 +593,24 @@ class Quadtile(SpatialFunctions):
             assert "geometry" in geometry
 
             for geom in geometry["geometry"].to_list():
+                geom = geometry["geometry"].to_list()[0]
                 geom_qk = self.latlon_to_quadkey(geom.centroid.y, geom.centroid.x, zoom=zoom)
                 if geom_qk == quadkey:
                     self.log.debug(
                         f"<[{pid}]> Found `{quadkey}` in {name}-geometries and classifying to {name}."
                     )
+                    # If there is a pure land or water tile, but the land or water geometry
+                    # is split, all geometry parts would resolve to the same tile quadkey and
+                    # the function would end up adding that same quadkey again for each
+                    # additional geometry part.
+                    # We want to add `quadkey` only on the first encounter.
                     if quadkey in quadkeys:
-                        raise ValueError(
-                            f"<[{pid}]> Duplicate quadkey `{quadkey}`. Cannot have the same quadkey more than once."
+                        self.log.warning(
+                            f"<[{pid}]> Duplicate quadkey `{quadkey}`. Cannot have the same quadkey more than once. Ignnoring."
                         )
-
-                    quadkeys += [quadkey]
-                    classifications += [classification]
+                    else:
+                        quadkeys += [quadkey]
+                        classifications += [classification]
 
     def classification_from_features(
         self, quadkeys, land=None, seawater=None, inlandwater=None, **kwargs