Params loading

tests/integration/test_single_node.py

@@ -1,4 +1,7 @@
+import pathlib
+
 import pytest
+import yaml
 
 import zntrack
 
@@ -26,6 +29,23 @@ def test_AddNumbers(proj_path, eager):
     assert add_numbers.state.loaded
 
 
+def test_AddNumbers_remove_params(proj_path):
+    with zntrack.Project() as project:
+        add_numbers = AddNumbers(a=1, b=2)
+
+    assert not add_numbers.state.loaded
+
+    project.run()
+
+    params = pathlib.Path("params.yaml").read_text()
+    params = yaml.safe_load(params)
+    params[add_numbers.name] = {}
+    params = pathlib.Path("params.yaml").write_text(yaml.dump(params))
+
+    with pytest.raises(zntrack.exceptions.NodeNotAvailableError):
+        add_numbers.load()
+
+
 @pytest.mark.parametrize("eager", [True, False])
 def test_AddNumbers_named(proj_path, eager):
     with zntrack.Project() as project:

zntrack/fields/zn/__init__.py

@@ -145,7 +145,7 @@ def get_data(self, instance: "Node") -> any:
         """Get the value of the field from the file."""
         file = self.get_files(instance)[0]
         params_dict = yaml.safe_load(instance.state.fs.read_text(file))
-        value = params_dict[instance.name].get(self.name, None)
+        value = params_dict[instance.name][self.name]
         return json.loads(json.dumps(value), cls=znjson.ZnDecoder)
 
     def get_stage_add_argument(self, instance: "Node") -> typing.List[tuple]: