A mistake to...sanction a country for invading their democratic neighbor for no other reason than imperial ambitions? A country that's kidnapping children en masse and flinging missiles at civilian targets while speedrunning their way to maximum war crimes?

No, it would've been wrong not to sanction Russia. The West's only mistake has been not sending arms to Ukraine even faster.

The problem is, is that it is just not Russia. Other countries are starting to learn that they could be sanctioned or cut off. Not only that the assets of private citizens can be seized easily. Wars happen, conflicts happen after all something similar could have been said about the Middle East.

No. It was a mistake for Russia to use technology from the west and not China.

If they were going to try and conquer their neighbors, then yes.

Western countries and businesses were happy to sell to Russia indefinitely before they attacked Ukraine.