livesync dumper does not handle exceptions correctly

livesync_data_dumper class connects to set irreversible and fork signals. In functions that service those signals SQL queries are executed without using data_processor, which means no separated threads are used to execute queries and no correct error handling is implemented. As a result in if SQL query fails, then the exception will be passed to the hived code instead of stopping the node by SIGINT signal - the node will continue working without break its execution.