Fix to display return value of handler (#427)

fixes #426

Author: abetomo

lib/main.js

@@ -122,7 +122,11 @@ event_sources.json and ${program.eventFile} files as needed.`)
     const nameSpace = createNamespace('AWSXRay')
     nameSpace.run(() => {
       nameSpace.set('segment', new AWSXRay.Segment('annotations'))
-      handler(event, context, callback)
+      const result = handler(event, context, callback)
+      if (result != null) {
+        console.log('Result:')
+        console.log(JSON.stringify(result))
+      }
     })
   }