WiredTiger should dump the hex dump of the page image that it read from disk if decoding its contents fails. We should use a similar (if not identical) mechanism that we use when encountering a checksum validation failure. For example, we should do this if __wt_page_inmem encounters an illegal page type.

Since page decoding happens after we validated the checksum, encountering a failure afterwards implies a bug in reconciliation (when the page image was constructed) or a memory corruption after the page was read and the checksum was validated. Dumping the page contents to the log would thus help us to diagnose the nature of the corruption.