I've run into this problem a couple of times. I'm indexing some data, but I've inadvertently added a field that my schema doesn't define. Everything seems to process fine, Solr doesn't complain, and then I spend time trying to figure out what's going on b/c I haven't realized my error. I've done this twice in the past few weeks now, costing me a few hours where a thrown error would have cost me only a few minutes.
Is this a known issue? I'm using a nightly build from a couple of weeks ago. Thanks, Jamie