Fix object_type return value (#2073)

Fixes https://app.shortcut.com/tiledb-inc/story/55930

tiledb/core.cc

@@ -1781,14 +1781,14 @@ void init_core(py::module &m) {
   m.def("datatype_size", &tiledb_datatype_size);
   m.def("as_built_dump", &as_built_dump);
   m.def("object_type",
-        [](const std::string &uri, const Context &ctx) -> py::str {
+        [](const std::string &uri, const Context &ctx) -> py::object {
           tiledb_object_t res;
           ctx.handle_error(
               tiledb_object_type(ctx.ptr().get(), uri.c_str(), &res));
           if (res == TILEDB_ARRAY) {
-            return std::string("array");
+            return py::str("array");
           } else if (res == TILEDB_GROUP) {
-            return std::string("group");
+            return py::str("group");
           }
           return py::none();
         });

tiledb/tests/test_util.py

@@ -165,3 +165,18 @@ def create_array(array_name, sparse):
         with self.assertRaises(tiledb.TileDBError) as excinfo:
             tiledb.ls(dense_arrays_uri, lambda x, y: 1 / 0)
         assert "ZeroDivisionError: division by zero" in str(excinfo.value)
+
+    def test_object_type(self):
+        uri = self.path("test_object_type")
+
+        # None case
+        self.assertIsNone(tiledb.object_type(uri))
+
+        # Array case
+        with tiledb.from_numpy(uri, np.arange(0, 5)) as T:
+            self.assertEqual(tiledb.object_type(uri), "array")
+        tiledb.Array.delete_array(uri)
+
+        # Group case
+        tiledb.group_create(uri)
+        self.assertEqual(tiledb.object_type(uri), "group")