ErrorRule and ExceptionRule currently calculates the rate of errors and exceptions. For errors we also determine the most common error.

For ExceptionRule we currently only look at the throwables statistics to calculate the rate. We should be able to also look at the thrown exceptions event (if enabled) to determine the most common exception.

For both errors and exceptions (again, if the thrown exceptions event is enabled) we should be able to print the top frames of the most common stack trace.