Is Ukraine safe to travel?

This is a poor answer, but EASTERN Ukraine, The Donbass, still sees Ukrainian shelling on Russian-populated places. Kiev has no riots, currently and is PROBABLY safe. West of there, to Lvov and surrounding areas should be safe.

EDIT: I looked thru TASS news and Googled Ukraine and of course got conflicting OPINION of right and wrong in the "occupation" of Donbass and Crimea. After a deadly coup, regardless if the vote to join Russia was "real" or not is meaningless. There has been no violence in Crimea, only tons of aid to rebuild the area. I suggest you Google on the areas you wish to visit and select "news" to see what is going on there. I think if you avoid Donbass, Lugansk and Donetsk areas, you will be OK.

As for Crimea, if you get a chance, DO go there. Remember though, IT IS RUSSIAN TERRITORY and you will need a Russuan visa for entry. Our son visited Artek, a summer camp in Crimea 2 or 3 times in 2016, '17, and '18. 

You not say Ukraine weak.

Green 666 by isotope rays is NOT forgivable; it leads to permanent hell. 666 is given with World Passport with no name on it (grey plastic card). Police 666 people on highways. Food stores and prisoners/insane asylum folks (released by the antichrist) 666 people too. Reject vaccines. Don't go into UFO to be healed by demons. Hide with Orthodox Christians to escape 666; leave all electronics behind so that antichrist's minions can't track you; burn documents as documents are from Satan

You'll need to define what you mean by "safe" and who you are worried about. There are occupied areas that you would need a Russian visa for anyway. The rest of the country is not under attack at the current time. The Russian were more likely to attack when Trump was in power since he was unlikely to oppose Putin. However, there are other issues- like crime, which is fairly high, and the road conditions are bad outside the major cities. Carry some cash to pay "bribes" when you get stopped by the police. 

Due to the current global pandemic, it's not safe to travel anywhere. If it's not essential, don't go.