fix: correctly raise KeyError for missing image-based feature

CHANGELOG

@@ -1,3 +1,6 @@
+0.13.3
+ - fix: correctly raise KeyError for missing image-based feature from
+   HDF5Data._image_cache
 0.13.2
  - fix: properly convert variable-length string logs in `copy_metadata`
 0.13.1

dcnum/read/hdf5_data.py

@@ -53,7 +53,11 @@ def __exit__(self, exc_type, exc_val, exc_tb):
 
     def __getitem__(self, feat):
         if feat in ["image", "image_bg", "mask"]:
-            return self.get_image_cache(feat)
+            data = self.get_image_cache(feat)
+            if data is None:
+                raise KeyError(f"Feature '{feat}' not found in {self}!")
+            else:
+                return data
         elif feat in self._cache_scalar:  # check for scalar cached
             return self._cache_scalar[feat]
         elif (feat in self.h5["events"]

tests/test_read_hdf5.py

@@ -97,6 +97,16 @@ def test_image_cache_iter_chunks(size, chunks, tmp_path):
         assert list(hic.iter_chunks()) == list(range(chunks))
 
 
+def test_keyerror_when_image_is_none(tmp_path):
+    path = tmp_path / "test.hdf5"
+    with h5py.File(path, "w") as hw:
+        hw["events/deform"] = np.random.rand(100)
+
+    h5dat = read.HDF5Data(path)
+    with pytest.raises(KeyError, match="image"):
+        _ = h5dat["image"]
+
+
 def test_pixel_size_getset(tmp_path):
     path = tmp_path / "test.hdf5"
     with h5py.File(path, "w") as hw: