Handle errors in Harvest.HarvestCycle.send_harvest/2

[sgessa]

This is an attempt to silent the error from Harvest.HarvestCycle.send_harvest/2 when the given supervisor is not started.

I wasn't able to reproduce this issue consistently.

Fixes #511

Example

exited in: GenServer.call(NewRelic.Harvest.Collector.CustomEvent.HarvesterSupervisor, {:terminate_child, #PID<0.1987228.0>}, :infinity)
    ** (EXIT) no process: the process is not alive or there's no process currently associated with the given name, possibly because its application isn't started

Stacktrace

  File "lib/gen_server.ex", line 1121, in GenServer.call/3
  File "lib/new_relic/harvest/harvest_cycle.ex", line 134, in anonymous fn/2 in NewRelic.Harvest.HarvestCycle.send_harvest/2
  File "lib/task/supervised.ex", line 101, in Task.Supervised.invoke_mfa/2

[CLAassistant]

All committers have signed the CLA.

[binaryseed]

When you see this, does it line up with when your app deploys? I'm wondering if it's related to the shutdown process that the agent attempts when the supervision tree is shutting down

[sgessa]

Yes it does

[binaryseed]

Closing in favor of #542 which does the same but avoids nested try blocks