Following on from that Guardian article, fairly unanimous criticism from both sides of the political spectrum in the UK press - this from the Telegraph's business editor:
Trump has committed sacrilege and set in motion a fateful chain of events
The President used his late-night declaration of victory before he had earned it to concoct a false narrative as an electoral fraud victim
www.telegraph.co.uk/business/2020/11/04/trump-has-committed-sacrilege-set-motion-fateful-chain-events/
(Apologies, pay-walled - but you can take out a month's free sub.)
Basically saying what various posters on here have said: this isn't a random mad set of tweets. This was pre-planned and is a deliberate strategy to try to subvert the democratic process.