message: Add types for styleElements object
diff: @@ -237,8 +237,8 @@ export async function setTheme(theme?: string): Promise<void> {
  // look for the stylesheet elements.
  // styleElements is a map from style name to HTMLLinkElement.
  - const styleElements = Object.create(null);
  - const themes = Array.from(document.querySelectorAll('[data-mx-theme]'));
  + const styleElements: Record<string, HTMLLinkElement> = Object.create(null);
  + const themes = Array.from(document.querySelectorAll<HTMLLinkElement>('[data-mx-theme]'));
  themes.forEach(theme => {
  styleElements[theme.attributes['data-mx-theme'].value.toLowerCase()] = theme;
  });
  