diff --git a/ops/model.py b/ops/model.py
index ec99173..c20d883 100644
--- a/ops/model.py
+++ b/ops/model.py
@@ -951,10 +951,10 @@ class Resources:
         """Fetch the resource from the controller or store.
 
         If successfully fetched, this returns a Path object to where the resource is stored
-        on disk, otherwise it raises a ModelError.
+        on disk, otherwise it raises a NameError.
         """
         if name not in self._paths:
-            raise RuntimeError('invalid resource name: {}'.format(name))
+            raise NameError('invalid resource name: {}'.format(name))
         if self._paths[name] is None:
             self._paths[name] = Path(self._backend.resource_get(name))
         return self._paths[name]

diff --git a/test/test_model.py b/test/test_model.py
index d243df3..01325d6 100755
--- a/test/test_model.py
+++ b/test/test_model.py
@@ -490,7 +490,7 @@ class TestModel(unittest.TestCase):
         self.harness.add_resource('foo', 'foo contents\n')
         self.harness.add_resource('bar', '')
 
-        with self.assertRaises(RuntimeError):
+        with self.assertRaises(NameError):
             self.harness.model.resources.fetch('qux')
 
         self.assertEqual(self.harness.model.resources.fetch('foo').name, 'foo.txt')

Failing to fetch a resource does not raise the expected exception 
According to the doc string and, as a consequence, the rtfm docs, `charm.model.resources.fetch` is expected to throw a `ModelError`. In reality, it's a `RuntimeError`. We should probably change either the docs or the exception raised.

https://github.com/canonical/operator/blob/9baf2ab3deafcaff5d9c6679cdf1d11fc88e3fa3/ops/model.py#L950-L960
test/test_model.py::TestModel::test_resources
test/test_model.py::TestModel::test_active_message_default test/test_model.py::TestModel::test_app_immutable test/test_model.py::TestModel::test_app_relation_data_modify_local_as_leader test/test_model.py::TestModel::test_app_relation_data_modify_local_as_minion test/test_model.py::TestModel::test_base_status_instance_raises test/test_model.py::TestModel::test_config test/test_model.py::TestModel::test_config_immutable test/test_model.py::TestModel::test_get_relation test/test_model.py::TestModel::test_is_leader test/test_model.py::TestModel::test_local_set_valid_app_status test/test_model.py::TestModel::test_local_set_valid_unit_status test/test_model.py::TestModel::test_model_attributes test/test_model.py::TestModel::test_model_name_from_backend test/test_model.py::TestModel::test_our_unit_is_our test/test_model.py::TestModel::test_peer_relation_app test/test_model.py::TestModel::test_pod_immutable test/test_model.py::TestModel::test_pod_spec test/test_model.py::TestModel::test_relation_data_del_key test/test_model.py::TestModel::test_relation_data_del_missing_key test/test_model.py::TestModel::test_relation_data_modify_our test/test_model.py::TestModel::test_relation_data_modify_remote test/test_model.py::TestModel::test_relation_data_type_check test/test_model.py::TestModel::test_relation_no_units test/test_model.py::TestModel::test_relation_set_fail test/test_model.py::TestModel::test_relations_immutable test/test_model.py::TestModel::test_relations_keys test/test_model.py::TestModel::test_remote_app_relation_data test/test_model.py::TestModel::test_remote_app_status test/test_model.py::TestModel::test_remote_unit_status test/test_model.py::TestModel::test_remote_units_is_our test/test_model.py::TestModel::test_resources_immutable test/test_model.py::TestModel::test_set_app_status_invalid test/test_model.py::TestModel::test_set_app_status_non_leader_raises test/test_model.py::TestModel::test_set_unit_status_invalid test/test_model.py::TestModel::test_status_eq test/test_model.py::TestModel::test_status_repr test/test_model.py::TestModel::test_storage test/test_model.py::TestModel::test_storages_immutable test/test_model.py::TestModel::test_unit_immutable test/test_model.py::TestModel::test_unit_relation_data test/test_model.py::TestModel::test_workload_version test/test_model.py::TestModel::test_workload_version_invalid test/test_model.py::TestApplication::test_planned_units test/test_model.py::TestContainers::test_unit_containers test/test_model.py::TestContainers::test_unit_get_container test/test_model.py::TestContainerPebble::test_add_layer test/test_model.py::TestContainerPebble::test_autostart test/test_model.py::TestContainerPebble::test_bare_can_connect_call test/test_model.py::TestContainerPebble::test_exec test/test_model.py::TestContainerPebble::test_get_plan test/test_model.py::TestContainerPebble::test_get_service test/test_model.py::TestContainerPebble::test_get_services test/test_model.py::TestContainerPebble::test_get_system_info test/test_model.py::TestContainerPebble::test_list_files test/test_model.py::TestContainerPebble::test_make_dir test/test_model.py::TestContainerPebble::test_pull test/test_model.py::TestContainerPebble::test_push test/test_model.py::TestContainerPebble::test_remove_path test/test_model.py::TestContainerPebble::test_replan test/test_model.py::TestContainerPebble::test_restart test/test_model.py::TestContainerPebble::test_restart_fallback test/test_model.py::TestContainerPebble::test_restart_fallback_non_400_error test/test_model.py::TestContainerPebble::test_restart_no_arguments test/test_model.py::TestContainerPebble::test_socket_path test/test_model.py::TestContainerPebble::test_start test/test_model.py::TestContainerPebble::test_start_no_arguments test/test_model.py::TestContainerPebble::test_stop test/test_model.py::TestContainerPebble::test_stop_no_arguments test/test_model.py::TestContainerPebble::test_type_errors test/test_model.py::TestModelBindings::test_binding_by_relation test/test_model.py::TestModelBindings::test_binding_by_relation_name test/test_model.py::TestModelBindings::test_binding_no_iface_name test/test_model.py::TestModelBindings::test_dead_relations test/test_model.py::TestModelBindings::test_empty_bind_addresses test/test_model.py::TestModelBindings::test_empty_interface_info test/test_model.py::TestModelBindings::test_invalid_keys test/test_model.py::TestModelBindings::test_missing_bind_addresses test/test_model.py::TestModelBindings::test_missing_egress_subnets test/test_model.py::TestModelBindings::test_missing_ingress_addresses test/test_model.py::TestModelBindings::test_no_bind_addresses test/test_model.py::TestModelBackend::test_action_fail test/test_model.py::TestModelBackend::test_action_get test/test_model.py::TestModelBackend::test_action_get_error test/test_model.py::TestModelBackend::test_action_log test/test_model.py::TestModelBackend::test_action_log_error test/test_model.py::TestModelBackend::test_action_set test/test_model.py::TestModelBackend::test_action_set_dotted_dict test/test_model.py::TestModelBackend::test_action_set_duplicated_keys test/test_model.py::TestModelBackend::test_action_set_error test/test_model.py::TestModelBackend::test_action_set_key_validation test/test_model.py::TestModelBackend::test_action_set_more_nested test/test_model.py::TestModelBackend::test_action_set_nested test/test_model.py::TestModelBackend::test_application_version_set test/test_model.py::TestModelBackend::test_application_version_set_invalid test/test_model.py::TestModelBackend::test_invalid_metric_label_values test/test_model.py::TestModelBackend::test_invalid_metric_labels test/test_model.py::TestModelBackend::test_invalid_metric_names test/test_model.py::TestModelBackend::test_invalid_metric_values test/test_model.py::TestModelBackend::test_is_leader_refresh test/test_model.py::TestModelBackend::test_juju_log test/test_model.py::TestModelBackend::test_local_set_invalid_status test/test_model.py::TestModelBackend::test_network_get test/test_model.py::TestModelBackend::test_network_get_errors test/test_model.py::TestModelBackend::test_relation_get_juju_version_quirks test/test_model.py::TestModelBackend::test_relation_get_set_is_app_arg test/test_model.py::TestModelBackend::test_relation_remote_app_name_env test/test_model.py::TestModelBackend::test_relation_remote_app_name_script_errors test/test_model.py::TestModelBackend::test_relation_remote_app_name_script_success test/test_model.py::TestModelBackend::test_relation_set_juju_version_quirks test/test_model.py::TestModelBackend::test_relation_tool_errors test/test_model.py::TestModelBackend::test_status_get test/test_model.py::TestModelBackend::test_status_is_app_forced_kwargs test/test_model.py::TestModelBackend::test_status_set_is_app_not_bool_raises test/test_model.py::TestModelBackend::test_storage_tool_errors test/test_model.py::TestModelBackend::test_valid_metrics test/test_model.py::TestLazyMapping::test_invalidate