Function customThemeSlugFromId

packages/shared-domain/src/custom-themes.ts:220–223

(themeId: string)

/** Slug embedded in a `custom-<slug>` theme id, or null for built-ins. */
export function customThemeSlugFromId(themeId: string): string | null {
  const m = CUSTOM_ID_RE.exec(themeId)
  return m ? m[1] : null
}

/** Whether a theme id refers to a custom theme. */
export function isCustomThemeId(themeId: string): boolean {