message: DidChangeConfigurationNotification fails with single segment keys
diff: @@ -2387,7 +2387,7 @@ class ConfigurationFeature implements DynamicFeature<DidChangeConfigurationRegis
  if (index >= 0) {
  config = Workspace.getConfiguration(key.substr(0, index), resource).get(key.substr(index + 1));
  } else {
  - config = Workspace.getConfiguration(key, resource).get('');
  + config = Workspace.getConfiguration(undefined, resource).get(key);
  }
  if (config) {
  let path = keys[i].split('.');
  