Polling service does not exit with non-zero code at error

[tyagishuchi1]

Polling service does not catch the error and hence get's stuck at one block with the above error message.

Expected Behavior

It should catch the error and exit the process with a non-zero code.

Steps to Reproduce

1. Run thor test node on the local machine.
   bin/thor --network test --api-timeout 10
2. Connect it to the polling service by adding it's URL in the .env.polling file in the root folder.
3. Run the service.
   socker-compose up -d polling_rtr
4. Stop the thor node.

[ashishjur]

We weren't able to reproduce unhandled promise error reliably. With current fix of using node flag, it behaves as expected. I think we should close this.

I'm removing myself from this. If any input is needed from me, please assign/tag.