Don't vigilantes, by definition, work outside the law?

It's complicated. If I put up spikes to prevent people entering my garage, is that vigilantism?

Is it vigilantism to exterminate a beehive that a vandal drops on my customer's property?

If the spikes somehow lock the garage closed, that's security. If they're instead designed to impale people who force it open that's going to be illegal in most places even if trespassing is also a criminal offence there. Not least because the law may authorise people to force that garage open, and it doesn't want authorised people getting hurt, regardless of how you feel about that.