safeTempName function
Returns a short random string suitable for temp file names (alphanumeric).
Implementation
String safeTempName({int length = 12}) {
const String chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
return List.generate(length, (_) => chars[_random.nextInt(chars.length)]).join();
}