French politicians have warned about the risk posed by the country’s increasingly violent and toxic rows over immigration after the mayor of a seaside town resigned following death threats and an arson attack on his home, and far-right groups protested over an asylum-seeker centre in his town. Yannick Morez announced he was stepping down as mayor of Saint-Brevin-les-Pins in western France, and would have to stop his work as a local doctor, weeks after his home was targeted in an arson attack that burned two cars and the front of his family house. The arson attack is still under investigation,...