That's why we try to build up our pantry, so we have things when we can't get them in stores, or afford to buy them. Losing your job is far easier on you if you have a well stocked pantry that you could live off for a while, rather than buying groceries.
Should a full depression hit, those with emergency food stores will be able to use them, rather than face empty store shelves or no money.
Even supplementing what you buy with your emergency supplies will make things easier when the goods in stores are limited