Prevent faulty data

python-package/lightgbm/basic.py

@@ -4936,6 +4936,9 @@ def refit_tree_manual(
         """
         values = _list_to_1d_numpy(values, dtype=np.float64, name="leaf_values")
 
+        if len(values) != self.num_leaves(tree_id):
+            raise ValueError("Length of values should be equal to the number of leaves in the tree")
+
         _safe_call(
             _LIB.LGBM_BoosterRefitTreeManual(
                 self._handle,