They haven't gone bust. They have suspended their shares and calling in administrators and hope to find a buyer.
"Going bust" is a colloquial term which just translates to "insolvent". Insolvent means a company can't pay it's debts as and when they fall due.
There are different forms of insolvency, the most common two are administration and liquidation. Liquidation is where a company is "wound up" - it ceases to trade immediately, all the assets are sold off/debts called in to try and get as much cash together to pay off as many of the bills and the insolvency practitioners' massive bills as possible. The company then ceases to exist.
Administration is where the company continues to trade in the hope of finding a buyer for it, either in whole or in part. If they can't then it will go into liquidation but I would imagine a brand like Joules would be quite marketable, if someone could turn it round. Administration wipes a company's debt slate clean which gives it a chance of survival.
Insolvency isn't necessarily some dark portent of terrible times to come; companies "go bust" even in the good times. Often it's as a result of poor business decisions and yes, an economic downturn can speed up that process or push a company over the brink when it might otherwise have clung on, but the underlying causes are still there. It doesn't at all mean other similar companies - White Stuff, Fat Face, Seasalt etc - are going to follow.