Spanish government orders GitHub to take down Tsunami Democràtic repository

Executing your elected mandate is not embezzlement. Calling a spade a fish does not make it a fish, even if the courts of law in your state agree with you. If the government of Catalonia was not competent to hold a referendum, they should have been dismissed. (The central government in Spain retains that authority.)

If it was not politically possible to dismiss them, then spending public resources on a policy which is the raison d'etre for the governing parties but which is outside the competence of that government should merely be considered a cost of the distribution of power.

Other democracies constantly have disputes about whether such a use of funds is within the competence of a specific government. And they find that, no, it is not within the competence of a specific government. And they manage to cope without charging anyone with embezzlement despite the money having been irrecoverably spent.

If this is too much for Spain, then Spain should remove the statutes of autonomy.

I understand this argument but find it brittle.

Firstly, yes, empires can be good for peace in some ways. The Roman Empire had Pax Romana. But the Soviet Union was also internally fairly peaceful, at least as much if not much more than the Roman Empire. Oddly enough, lots of people didn't want to be a part of either empire. There are downsides to empires that outweigh enforced "peace".

Secondly:

EU is not an empire and it is not trying to be

I think you missed a possibility: the EU is not an empire yet but is trying to be, and this is already causing various kinds of conflict. The fact that it's not creating World War 3 is no excuse: the Soviets didn't cause World War 3 either but not many people think the USSR was a good thing.

For an empire to dominate people it must have at least two things. One, a large number of people physically within that population who are loyal to the regime. Two, military strength to swiftly put down any rebellions and ensure the loyalists remain in power.

The EU has the first in abundance, as the horrible situation in the UK is showing. People were given a vote. The British establishment are refusing to implement it, as they're more loyal to the EU than to their own voters. This is no surprise because the same pattern is observed throughout Europe, where the EU creates a constant series of constitutional crises. Democracy is being crushed throughout the continent without a shot being fired due to the massive weight of regime loyalists already in positions of power.

The EU doesn't yet have the second. But it wants it very, very badly and has identified an EU army which reports directly to the Commission as its new top priority. Why does the EU need an army when NATO exists and works? Nobody can quite explain that. But let's face it: people keep voting in anti-EU politicians throughout Europe and if current trends continue, eventually one of these power struggles will be lost by the loyalists. The only way the EU could then keep control is by suppressing anti-EU citizens through force. If the local police won't do it, an EU army will be ready to step in and enforce Commission policy. It's hardly going to be useful for major conflict anytime soon given its size and newness, but as a form of ultra-loyal police it won't be half bad.

I'm personally planning based on the belief that the EU will be a new USSR-style empire before I reach retirement, complete with ability to put down insurrections, a large propaganda apparatus and ideological loyalty of at least 100 million people. I expect to die of old age with it firmly in control of most of Europe.

Finally:

Second: The collaboration between countries is not mandatory to be an empire as form.

I completely agree, so why are we building one? The useful work the EU does could be better done by a constellation of standards bodies and independent political alliances. The politics of unity and Europeanism that comes with it is unnecessary and dangerous.

Read that report you linked. According to it, most Catalans are not so eager to leave as you say (and I would not call it an impartial source). For example, in page 4 you can clearly see: 43.6% wants an independent Catalunya, but 48.2% wants to remain being a part of Spain.

Why is the tyranny of the majority wrong (this is what most people would call democracy) but you see no problem with the tyranny of a minority?

No, current constitution was redacted after the death of the dictator. There were mainly seven people involved in writing it. Between them, there was a communist, a socialist, a representative of the Basque and Catalan minorities, and only one who came from previous governments during the dictatorship. By the way, two of these seven people (the communist one and the representative of Basque-Catalan minorities) were from Catalonia (this is almost the perfect proportion taking into account the fraction of Spain that Catalonia represents, but if you know that Spain has 17 autonomous regions, it is obvious that Catalonia was not misrepresented).

You will read several comments here saying similar things (I have read something like that this constitution was only voted because the only other option was another war), but it is simply not true, as you can easily check in any independent source.

The status quo was already established by a very qualified majority. Changing it should require a qualified majority too.

It's the same reason a thermostat is not constantly switching on and off when you cross the set temperature. Heating will start when you go a couple of degrees below the desired temperature, and it will only stop when you reach a couple of degrees more. Else, you have an unstable system (this is not my opinion, it's very basic control systems theory).