SPARQL-over-HTTP errors should be surfaced in the log/response

[ash-mcc]

Background

I added xtdb-rdf 1.19.0 lib to xtdb-in-a-box 0.0.2 (xtdb-core 1.19.0)’s deps.edn. Then, against it, curl http://localhost:9999/_xtdb/status was successful. But curl http://localhost:9999/_xtdb/sparql?query=SELECT ?o WHERE { ?s ?p ?o . } failed with an UnsupportedOperationException. (I did URLEncode that query arg when I actually try it.) Jetty’s DEBUG log entries showed the corresponding incoming HTTP request but they didn’t help me to figure out what the problem might be. More logging?...

The cause of the Exception

xtdb.sparql/sparql->datalog throws (line 223) an UnsupportedOperationException with the message Does not support variables in predicate position: ?p. But that message isn't surfaced in the logs or the HTTP response.

TODO

Jeremy suggested that I created this issue to have that message surfaced in the logs.