What! And take the sensitive, appropriate-for-your-aged-grandmother notes out of solrconfig.xml? To whit:
<!-- If a 'dir' option (with or without a regex) is used and nothing
is found that matches, it will be ignored
<lib dir="/total/crap/dir/ignored" />
Which is more than a little inconsistent with what follows:
<!-- an exact 'path' can be used instead of a 'dir' to specify a
specific jar file. This will cause a serious error to be logged
if it can't be loaded.
<lib path="../a-jar-that-does-not-exist.jar" />
Why should failing to find a specific jar log a serious error but a directory be ignored?
Seriously, let's complain if the dir isn't found, at least log a warning if not an error/exception. Fail early, fail often.