health: Fix yet another NRE and improve panic handling

[victorges]

This fixes another NRE found on the media server metrics code, which for some reason are getting some nil values sometimes.

Since we've been getting some of these frequently I also made some improvemenets to the panic handling code:

• On the "rabbitmq stream consumer", include the message data in the panic log
• On the "health core", recover from panics in reducers and skip the event instead of restarting the app

[gioelecerati]

LGTM