Unhandled NullPointerException if request is for an unknown query ID

[vaultah]

trino-gateway may fail with an unhandled NPE if it's unable to find the routing group for a particular query ID.

jakarta.servlet.ServletException: com.google.common.util.concurrent.UncheckedExecutionException: java.lang.NullPointerException
    ...
    at java.base/java.lang.Thread.run(Thread.java:1447)
Caused by: com.google.common.util.concurrent.UncheckedExecutionException: java.lang.NullPointerException
    at com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2074)
    at com.google.common.cache.LocalCache.get(LocalCache.java:3986)
    at com.google.common.cache.LocalCache.getOrLoad(LocalCache.java:4007)
    at com.google.common.cache.LocalCache$LocalLoadingCache.get(LocalCache.java:4946)
    at io.trino.gateway.ha.router.RoutingManager.findRoutingGroupForQueryId(RoutingManager.java:194)
    at java.base/java.util.Optional.map(Optional.java:260)
    at io.trino.gateway.ha.handler.RoutingTargetHandler.lambda$resolveRouting$0(RoutingTargetHandler.java:86)
    at java.base/java.util.Optional.map(Optional.java:260)
    at io.trino.gateway.ha.handler.RoutingTargetHandler.resolveRouting(RoutingTargetHandler.java:85)
    at io.trino.gateway.proxyserver.RouteToBackendResource.postHandler(RouteToBackendResource.java:67)
    ...
    ... 37 more
Caused by: java.lang.NullPointerException
    at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:902)
    at com.google.common.cache.LocalCache.put(LocalCache.java:4212)
    at com.google.common.cache.LocalCache$LocalManualCache.put(LocalCache.java:4872)
    at io.trino.gateway.ha.router.RoutingManager.setRoutingGroupForQueryId(RoutingManager.java:122)
    at io.trino.gateway.ha.router.RoutingManager.findRoutingGroupForUnknownQueryId(RoutingManager.java:264)
    at io.trino.gateway.ha.router.RoutingManager$2.load(RoutingManager.java:85)
    at io.trino.gateway.ha.router.RoutingManager$2.load(RoutingManager.java:81)
    at com.google.common.cache.LocalCache$LoadingValueReference.loadFuture(LocalCache.java:3551)
    at com.google.common.cache.LocalCache$Segment.loadSync(LocalCache.java:2302)
    at com.google.common.cache.LocalCache$Segment.lockedGetOrLoad(LocalCache.java:2177)
    at com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2068)
    ... 66 more

Essentially, findRoutingGroupForQueryId may return null (e.g. if the query has already been removed from history), in which case LocalCache.put will fail due to null value.