I see the Guardian is back to peddling the old nonsense that an independent Scotland would have to use the Euro.
Here's the thing: all EU members (except the UK and Denmark, who have formal opt-outs) have to commit to using the Euro... at some point. But there is no fixed timescale for adopting it. Moreover, there are economic requirements for adopting the Euro, so all EU countries have a de facto opt-out - just arrange your economy such that you never quite meet those requirements and the job is done. (Also, see: Bulgaria, Croatia, the Czech Republic, Hungary, Poland, Romania, and Sweden.)
(It's worth noting that the EU have bent their rules in the past to allow countries in that didn't comply. They won't be doing that again, since the highest-profile country in that position is Greece.)
The upshot of that is that not only would an independent Scotland not have to use the Euro, an independent Scotland would not be allowed to use the Euro.
And that's all easily established simply by checking the appropriate documentation. Anyone peddling that line either doesn't know what they're talking about, or they're deliberately lying. Either way, they can be safely ignored. (But, yeah, fake news is obviously the province of social media and other unreliable sources; a reputable newspaper such as The Guardian would never stoop so low - I'm sure they rigorously fact check everything they publish.)
But the funniest thing about that is probably that the whole attack line is entirely backwards. Because the Euro, despite its problems, is a well-established and more or less stable currency. Indeed, given the shocks Sterling has taken in the past year, it's hard to argue that it's less stable than the currency we already use.
Meanwhile, an independent Scotland within the EU* almost certainly couldn't, and wouldn't want to, continue to use Sterling - it was one thing to propose a currency union in 2014 when both iScotland and rUK would be running similar economies and both in the EU. But when iScotland is in the EU*, rUK is out, and the economies are significantly divergent it just doesn't make sense.
So, really, iScotland switching to use the Euro* would probably have been the next best option, if it was possible. But since that's not an option, and if Sterling also doesn't make sense, that's something of an issue - indeed, probably the single biggest issue that any independence campaign is going to have to face: they're going to have to sell people on the notion of establishing a whole new currency, with all that that entails.
"You'll have to use the Euro!" is frankly a rather bizarre threat.
* All of this assumes that iScotland would be in the EU, which is of course by no means guaranteed. But that's another topic for another day... one I'll probably not bother with.