MetricsCollector.apply() does not report exceptions from custom collector creation

When custom collector class is specified and fallback collector is allowed, MetricsCollector.apply() attempts to instantiate it in a TryNative. If it fails, it simply instatiates the fallback collector without reporting the problem. It should log the exception with stack trace.

We've discovered by accident that some of our non-critical metrics were not collected because of this --- without any indication in the logs.