set exitCode instead of force exit on serial error

Author: lukeed

lib/reporter.js

@@ -76,7 +76,7 @@ module.exports = function () {
 		})
 
 		.on("serial_error", () => {
+			process.exitCode = 1
 			$.error("Task chain was aborted!")
-			process.exit(1)
 		})
 }