RESTXQ: NullPointerException

[ChristianGruen]

Test cases RestXqPathTest.pathVar, RestXqParamTest.queryParamsErrors:

java.lang.NullPointerException
	at org.basex.core.locks.Locking.release(Locking.java:146)
	at org.basex.core.jobs.Job.unregister(Job.java:61)
	at org.basex.http.restxq.RestXqResponse.finish(RestXqResponse.java:152)
	at org.basex.http.web.WebResponse.create(WebResponse.java:63)
	at org.basex.http.restxq.RestXqServlet.run(RestXqServlet.java:72)

Possibly caused by 69d51e5.

…and a possible reason why rest:forward does not work as expected anymore.