Avoid a NullPointerException...

If we don't do an early exit after line 30, line 36 (37 above) will throw an NPE... 
(Another way would be to throw new IOException(e) instead of printStacktrace)

Author: eranation

samples/spring/pet-store/src/main/java/com/amazonaws/serverless/sample/spring/StreamLambdaHandler.java

@@ -28,6 +28,7 @@ public void handleRequest(InputStream inputStream, OutputStream outputStream, Co
             } catch (ContainerInitializationException e) {
                 e.printStackTrace();
                 outputStream.close();
+                return;
             }
         }