Various options available:
1. Use a reinforced tire in the first place. Maybe you can carefully and slowly ride home or to next dealer on the "flat" tire.
2. If it´s just a puncture by a nail or small screw in the thread you might also just refill with air and get along for another short while.
3. You could maybe use liquid tire sealant stuff. I would use that only in a life threatening emergency, because this stuff makes a big mess inside the tire and the rim. Huge job to clean up afterwards.
4. You could also remove the nail or screw and repair it with the tire plug repair kit. Takes about 5 min. on the sidewalk to do it. Videos herefore are available on youtube.
5. If the bad valve stem was the cause, replace it more often with quality valve stems, or at least whenever you change the tire. Cheap chinese valve stems tend to go bad much earlier.
6. If your tire has got larger cuts and cracks you might be happy having an AAA coverage and call a tow truck or call somebody else to pick you and your scooter up.
7. Check your tires for wear, punctures cuts and cracks on a regular basis, so you will always be up to date about the condition of your tires.
8. Don´t let tires get too old. After 6 years of age you seriously should think about replacing it. Check DOT number on sidewall.