Senate leaders are racing to unravel last-minute snags in a $2 trillion economic rescue package to ease the financial pain of the coronavirus epidemic. The measure is the largest economic relief bill in history. Both parties’ leaders are pushing for quick passage so they can get the legislation to the House and freed up for the country. But several conservative Republican senators want late changes. They say the bill as written could provide an incentive for companies to lay off workers. They want the bill altered to ensure that employees don’t earn more money if they’re laid off than if they’re working.