If the method ( RFC call ) is not successful only the navigation directs to the default error screen. You can follow any of these 3 ways.
1.If the list is empty you can handle it using the box provided in the HWC designer itself.
2.Else if you want to push the error message from RFC you need to return error "E" in the response of the error instead of filling the error table. Hence the HWC app itself take care of showing the error message you are mentioning in the other code.
3.Another way is using a conditional success screen navigation available i the HWC.
There is a sample of Conditional Navigation in the following sample.
https://cw.sdn.sap.com/cw/docs/DOC-151007
- Midhun VP