Stack traces in the turbine heat sensor sample

[fpj]

We have a couple of instances of printing stack traces that seem arbitrary. They don't seem to be doing anything with respect to helping the user understand what has gone wrong and what to do next. It feels like "I'm not sure what to do with it, so let me print the stack trace".

The instances I'm talking about are:
https://github.com/pravega/pravega-samples/blob/develop/scenarios/turbine-heat-sensor/src/main/java/io/pravega/turbineheatsensor/TurbineHeatSensor.java#L414
https://github.com/pravega/pravega-samples/blob/develop/scenarios/turbine-heat-sensor/src/main/java/io/pravega/turbineheatsensor/TurbineHeatSensor.java#L445

The first one is an error while writing in the context of a txn. If the write fails, then should it really keep going? The txn is in an inconsistent state and it feels like a fatal error for the application.

The second one is a reinitialization required for a reader, which happens when a reader groups is reset. We shouldn't simply print the stack trace and move on. We should either reinitialize or exit in the case that reinitializing is a problem. If it is not expected, then exiting sounds the right thing to do, but simply swallowing the exception is wrong.