fix: propagate frame-level data modifier failures

deepmd/utils/data.py

@@ -530,6 +530,9 @@ def get_single_frame(self, index: int, num_worker: int) -> dict:
                     frame_data,
                     self,
                 )
+                # propagate any exception raised inside the modifier instead of
+                # silently returning (and caching) an unmodified frame
+                future.result()
             if self.use_modifier_cache:
                 # Cache the modified frame to avoid recomputation
                 self._modified_frame_cache[index] = copy.deepcopy(frame_data)

source/tests/common/test_deepmd_data.py

@@ -46,3 +46,41 @@ def test_remap_with_unused_types(self) -> None:
         loaded = data._load_set(self.set_dir)
         expected_sorted = expected_atom_types[data.idx_map]
         np.testing.assert_array_equal(loaded["type"], np.tile(expected_sorted, (1, 1)))
+
+
+class _RaisingModifier:
+    """A modifier whose ``modify_data`` always fails."""
+
+    use_cache = True
+
+    def modify_data(self, data: dict, data_sys: DeepmdData) -> None:
+        raise ValueError("modifier failure")
+
+
+class TestDeepmdDataModifierError(unittest.TestCase):
+    def setUp(self) -> None:
+        self.tmpdir = tempfile.TemporaryDirectory()
+        self.root = Path(self.tmpdir.name)
+        set_dir = self.root / "set.000"
+        set_dir.mkdir()
+        atom_types = np.array([0, 1], dtype=np.int32)
+        np.savetxt(self.root / "type.raw", atom_types, fmt="%d")
+        np.save(
+            set_dir / "coord.npy",
+            np.zeros((3, atom_types.size * 3), dtype=np.float32),
+        )
+        np.save(
+            set_dir / "box.npy",
+            np.tile(np.eye(3, dtype=np.float32).reshape(9), (3, 1)),
+        )
+
+    def tearDown(self) -> None:
+        self.tmpdir.cleanup()
+
+    def test_get_single_frame_propagates_modifier_error(self) -> None:
+        data = DeepmdData(str(self.root), modifier=_RaisingModifier())
+        # a failing modifier must surface its error, not be swallowed
+        with self.assertRaises(ValueError):
+            data.get_single_frame(0, num_worker=1)
+        # and the unmodified frame must not be cached
+        self.assertNotIn(0, data._modified_frame_cache)