FORT WORTH, Texas — Inside a partially completed Amazon warehouse here, workers last summer walked on conveyor belts four stories high without safety harnesses, welders used plasma torches while surrounded by flammable cardboard boxes, and laborers raised metal racks alongside a moving forklift, putting their feet in danger of being crushed. Contractors and subcontractors who spoke to Stateline on condition of anonymity for fear of retaliation said supply chain issues and other COVID-19-related delays put the warehouse construction behind schedule. In the rush to complete the project on time, …