Linked but not a duplicate of this question.
An example of the problem
During the last Star-Wars movie, I was dumbfounded by the sheer stupidity of admiral Holdo's move, during this particularly visual scene:
While most people I know don't seem to realize how incredibly reckless this was, I'd like to offer one of my favorite quotes ever to summarize the situation:
Gunnery Chief: This, recruits, is a 20-kilo ferrous slug. Feel the weight. Every five seconds, the main gun of an Everest-class dreadnought accelerates one to 1.3 percent of light speed. It impacts with the force of a 38-kiloton bomb. That is three times the yield of the city buster dropped on Hiroshima back on Earth. That means Sir Isaac Newton is the deadliest son-of-a-bitch in space. Now! Serviceman Burnside! What is Newton's First Law?
First Recruit: Sir! An object in motion stays in motion, sir!
Gunnery Chief: No credit for partial answers, maggot!
First Recruit: Sir! Unless acted on by an outside force, sir!
Gunnery Chief: Damn straight! I dare to assume you ignorant jackasses know that space is empty. Once you fire this husk of metal, it keeps going till it hits something. That can be a ship, or the planet behind that ship. It might go off into deep space and hit somebody else in ten thousand years. If you pull the trigger on this, you're ruining someone's day, somewhere and sometime. That is why you check your damn targets! That is why you wait for the computer to give you a damn firing solution! That is why, Serviceman Chung, we do not "eyeball it!" This is a weapon of mass destruction. You are not a cowboy shooting from the hip!
Second Recruit: Sir, yes sir!
(Emphasis mine - quote from an anonymous human military on the Citadel in Mass Effect 2)
So, for those who've been sleeping in the back of the classroom during their physics class, Holdo accelerating a ship at a speed faster than light and ramming it into another ship is the equivalent of a cosmic shotgun. (Hence the pretty little light streaks scattering in a cone from the impact point and instantly destroying Star Destroyers).
A single bolt of 1g from this ship now has a bare minimum kinetic energy of $E = 0.5 \times m \times C^2 = 0.5 \times 0.001 \times 9 \times 10^{16} = 4.5 \times 10^{13} J$. 1
(A kiloton is $4,184 \times 10^{12} J$, so the absolute minimum energy on impact, if physics didn't break at that point, as explained in comment is around 10 kilotons. Hiroshima's Little Boy was estimated between 12 and 15 kilotons).
To be honest, I'm not even sure this law holds at speeds higher than light, and I don't have the theoretical knowledge to even make an educated guess.
Given that some several-years travel at the speed of light could be done in mere hours in the SW universe, I'd posit that those numbers are way higher, and each bolt (not even talking about chunks of the ship) are now delayed orbital strikes aiming god knows where.
At this point, you might as well charge the Rebellion for crime against the universe. No wonder why the Yuuzhan-Vongs paid us a visit.
Problem
The other question explains perfectly the problem. As soon as your universe includes FTL travel, an idiot somewhere is gonna make this mistake (on purpose or not) and a lot of people are gonna pay for it.
Following the example above, I struggle to create any universe with FTL travel, because each war would mean I'd have to wipe half of the celestial map.
A few propositions to protect a planet or a system from this kind of incident includes: giving the person using FTL the means to avoid said incident, trusting them to understand the risks, pre-emptive strike, or (my favorite) clouds of space dust.
Now, the two first answers are made irrelevant by idiocy. Holdo knew the risks and had the computers telling her not to do it. By hubris, despair or idiocy, someone in a space battle will end up pushing the red button. (You don't even have to sacrifice a pilot. Guided FTL rockets are the end-game)
Pre-emptive strike seems a bit radical. While they're targeted and shouldn't cause collateral damage, you can't just destroy every planet where FTL "might" happen.
The cloud of dust is useful to protect a single system or planet, but there is no way to effectively shield the universe, unless you want to fill all empty space with space dust.
Is there any way to devise a universe with FTL travel without realistically condemning half of said universe to utter destruction by FTL strikes? (Not asking how to shield a sole planet / a sole civilisation from a dumb accident)
Note that any reactionary counter measure suggests you know that a danger is coming your way. The problem of FTL is that the danger travels faster than the information. You'll "see" the explosion way after the upper deck of the destroyer tore through your planet. And the one behind. And the one behind the one behind. (But maybe quantum entanglement can help. I've read somewhere about research being done on the topic to communicate faster than light, but I don't understand the principle behind it).
To clarify what I'm asking for, I'm looking for references of universes with non-destructive faster than light space-travel, effective countermeasures covering the universe, or anything that allows you to write a story including both FTL and idiots without dramatic consequences.
1 Fixed thanks to elPolloLoco's answer. Don't do maths absent-mindedly during lunch break without double checking the data.