Currently, when a plugin throws an exception, say an IllegalArgumentException, then that bubbles all the way up and fails the mapper or reducer and with that the entire job. It is ok to fail the pipeline, but the error should be logged so that it appears in the pipeline logs.
This happens, for example, when a plugin attempts to set a non-nullable field to null. That is a common error that users should be able to find in the logs.
Currently, that exception is only visible in the YARN console.