Fix pytest UnraisableExceptionWarning (#916)

requirements.txt

@@ -1,8 +1,8 @@
 # pinned dependencies to reproduce an entire development environment to use HDMF
-h5py==3.8.0
-importlib-resources==5.12.0; python_version < "3.9"  # TODO: remove when when minimum python version is 3.9
-jsonschema==4.17.3
-numpy==1.24.3
-pandas==2.0.1
-ruamel.yaml==0.17.24
-scipy==1.10.1
+h5py==3.9.0
+importlib-resources==6.0.0; python_version < "3.9"  # TODO: remove when minimum python version is 3.9
+jsonschema==4.18.4
+numpy==1.25.1
+pandas==2.0.3
+ruamel.yaml==0.17.32
+scipy==1.11.1

src/hdmf/container.py

@@ -194,8 +194,11 @@ def __gather_fields(cls, name, bases, classdict):
 
     def __del__(self):
         # Make sure the reference counter for our read IO is being decremented
-        del self.__read_io
-        self.__read_io = None
+        try:
+            del self.__read_io
+            self.__read_io = None
+        except AttributeError:
+            pass
 
     def __new__(cls, *args, **kwargs):
         """

tests/unit/test_container.py

@@ -131,6 +131,13 @@ def test_get_read_io_on_parent(self):
             self.assertIsNone(child_obj.read_io)
             self.assertIs(child_obj.get_read_io(), temp_io)
 
+    def test_del_read_io(self):
+        class TestContainer(AbstractContainer):
+            def __init__(self):
+                raise ValueError("Error")
+        with self.assertRaises(ValueError):
+            TestContainer()
+
     def test_set_parent(self):
         """Test that parent setter properly sets parent
         """