message: Fix setTheme types
diff: @@ -176,7 +176,7 @@ export function getCustomTheme(themeName: string): ICustomTheme {
  *
  * @param {string} theme new theme
  */
  -export async function setTheme(theme: string): Promise<void> {
  +export async function setTheme(theme?: string): Promise<void> {
  if (!theme) {
  const themeWatcher = new ThemeWatcher();
  theme = themeWatcher.getEffectiveTheme();
  