We have tested the scenario as per your description i.e. when the app is in the background, notifications are still received and app does not crash.
The only difference is we've used our own server implementation using node.js, as we could not get yours to run (expecting registration ID as input?!) I've attached our testing server and application for your convenience.
You should install node.js and starting the server is done through console cmd: node sampleserver.js.
Make sure to change the API key in sampleserver.js and update the IP address in index.js to the IP address of your machine that would be used as server.
All the best,
the Telerik team
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