Check if the logger/error handler is bullet-proof

[svinniks]

Both logger and error handler may not fail with an exception. Especially protection against unhandled exceptions must be developed while calling custom handlers/formatters/resolvers.
The main goal is to avoid exception handling at all. For example, when there is an attempt to register a NULL handler it is better to do nothing, rather than to raise an exception, therefore making it impossible to initialize the LOG$ package.
It would be very nice to have some table which would log exceptions raised from the handlers/resolvers/formatters.