Raise a clear exception when the wrong type is passed to the function

src/lib.rs

@@ -22,7 +22,15 @@ fn polygon_to_geohashes(
 
     let mut polygons = Vec::<Polygon<f64>>::new();
 
-    let geom = py_polygon.extract::<Geometry>()?;
+    let geom: Geometry = match py_polygon.extract::<Geometry>() {
+        Ok(geometry) => geometry,
+        Err(e) => {
+            return Err(pyo3::exceptions::PyValueError::new_err(
+                format!("Exception while trying to extract Geometry. This function requires a Shapely Polygon or MultiPolygon. ({:?})", e
+            )))
+        }
+    };
+
     if let Err(e) = {
         match geom.0 {
             GtGeometry::Polygon(polygon) => {

tests/test_geohasher.py

@@ -3,9 +3,15 @@
 from polygon_geohasher.polygon_geohasher import (
     polygon_to_geohashes as polygon_to_geohashes_py,
 )
+import pytest
 
-# def test_invalid():
-#    assert geohash_polygon.polygon_to_geohashes("bouya", 3, True) == set()
+
+def test_exception_when_invalid():
+    with pytest.raises(
+        ValueError,
+        match=r"Exception while trying to extract Geometry. This function requires a Shapely Polygon or MultiPolygon.*",
+    ):
+        geohash_polygon.polygon_to_geohashes({}, 3, True)
 
 
 def test_simple_polygon():