A question came up on this list in June[1] about a crash in metadata provider. I just managed to reproduce the problem[2] and will check in a fix shortly.
Julian [1] https://mail-archives.apache.org/mod_mbox/incubator-calcite-dev/201506.mbox/%3chkxpr04mb2948aeb2a009c59f594690382...@hkxpr04mb294.apcprd04.prod.outlook.com%3E [2] https://issues.apache.org/jira/browse/CALCITE-874
