President Emmanuel Macron’s decision to call a snap parliamentary election in response to France’s extreme right’s victory in last month’s European elections was comparable to saying, “Let’s jump off the bridge to see if there is water in the river,” the French humorist Sophia Aram joked. In the hours preceding Sunday night’s election results, France is on the parapet, preparing to jump. Fear of street violence is the most salient in a welter of emotions. Interior minister Gérald Darmanin is deploying an extra 30,000 police and gendarmes – 5,000 in Paris – “so that the ultra-left or the ultra-right cannot...