So is the election campaigning still as annoying as it used to be? It was getting bad.
https://youtu.be/8-mbV6tiqIg
The presidential election is May 9.
As anyone who has done a risk management course would know, risk has two dimensions: likelihood and consequence.
As others have mentioned, the likelihood of something happening is very low. In (almost) all likelihood you'll be fine.
The consequences if something did happen though are rather high. So what to do about that?
Just, 'being worried,' does no good. It will just ruin your holiday, so don't do that. Instead enjoy your trip and have some concrete plans in place so you know what to do in case of something happens. So what kind of plans?
Firstly, every Seoul (if that's where you are) subway station is a bomb shelter. Follow the crowd to there.
Secondly, get out of the country. Be prepared to leave the country at a moment's notice.
So at all times, have your passport with you and some very basic essentials like medication, money/credit card, layers of clothing, maybe a change of undies if you're feeling luxurious.
But how to get out? The airport will be everyone's first idea, but the state of airports could be anything ranging from normal service to not being there anymore. So know your secondary airports and at least know how to quickly buy a ticket for those flights. If ticket buying means using the internet, prepare for that to be slow if working at all. Oh have a spare battery pack for your phone that has its own internet connectivity.
Being in an aircraft while in the range of a ballistic missile will certainly be a test of nerves.
So alternatively consider a ferry. There are ferry services to Japan, Russia and China. China would be my choice. Shanghai is close and will have good transport options for your ongoing journey. Visas might be fiddly, but you can deal with that. So at least know how to get a ferry including secondary ports. If you're feeling paranoid or have a family to care for, you could buy some fully refundable tickets.
Thirdly, know what your travel insurance will cover and how to invoke it.
Fourthly, register with Smart Traveller so the government will know to go looking for you.
But really, nothing is likely to happen. Enjoy your trip and be wary of those sweetened pizzas they have in Seoul.