China's Covid-19 health code system that strictly governs people's movements crashed in Xi'an this week, worsening conditions in the locked-down city where the country's worst outbreak since Wuhan has been unfolding. The crash has complicated efforts to weed out cases through mass testing, created hurdles for people seeking care at hospitals and led to the suspension of a top official, the latest among a slew of bureaucrats to be punished as Beijing fumes over the situation.