khatru: fix bug that caused a query with limit zero to bypass request filtering.

spotted by hodlbod.

khatru/responding.go

@@ -12,11 +12,6 @@ import (
 func (rl *Relay) handleRequest(ctx context.Context, id string, eose *sync.WaitGroup, ws *WebSocket, filter nostr.Filter) error {
 	defer eose.Done()
 
-	if filter.LimitZero {
-		// don't do any queries, just subscribe to future events
-		return nil
-	}
-
 	// then check if we'll reject this filter (we apply this after overwriting
 	// because we may, for example, remove some things from the incoming filters
 	// that we know we don't support, and then if the end result is an empty
@@ -27,6 +22,11 @@ func (rl *Relay) handleRequest(ctx context.Context, id string, eose *sync.WaitGr
 		}
 	}
 
+	if filter.LimitZero {
+		// don't do any queries, just subscribe to future events
+		return nil
+	}
+
 	// run the function to query events
 	if nil != rl.QueryStored {
 		for event := range rl.QueryStored(ctx, filter) {