message: reset focus repr color params
  to element-symbol, when no theme given
diff: @@ -59,10 +59,8 @@ export namespace StructureRepresentationPresetProvider {
  }
  export function updateFocusRepr<T extends ColorTheme.BuiltIn>(plugin: PluginContext, structure: Structure, themeName: T | undefined, themeParams: ColorTheme.BuiltInParams<T> | undefined) {
  - if (!themeName && !themeParams) return;
  -
  return plugin.state.updateBehavior(StructureFocusRepresentation, p => {
  - const c = createStructureColorThemeParams(plugin, structure, 'ball-and-stick', themeName, themeParams);
  + const c = createStructureColorThemeParams(plugin, structure, 'ball-and-stick', themeName || 'element-symbol', themeParams);
  p.surroundingsParams.colorTheme = c;
  p.targetParams.colorTheme = c;
  });
  