Improve error handling

Signed-off-by: Tomasz Pietrek <tomasz@nats.io>

server/consumer.go

@@ -3267,7 +3267,6 @@ func (o *consumer) getNextMsg() (*jsPubMsg, uint64, error) {
 		return pmsg, 1, err
 	}
 
-	var lastErr error
 	// if we have filters, iterate over filters and optimize by buffering found messages.
 	for _, filter := range o.subjf {
 		if filter.nextSeq < o.sseq {
@@ -3323,23 +3322,24 @@ func (o *consumer) getNextMsg() (*jsPubMsg, uint64, error) {
 	// Grab next message applicable to us.
 	// Sort sequences first, to grab the first message.
 	filter := o.subjf[0]
+	err := filter.err
 	// This means we got a message in this subject fetched.
 	if filter.pmsg != nil {
 		filter.currentSeq = filter.nextSeq
 		o.sseq = filter.currentSeq
 		returned := filter.pmsg
 		filter.pmsg = nil
-		return returned, 1, filter.err
+		return returned, 1, err
 	}
-	if filter.err == ErrStoreEOF {
+	if err == ErrStoreEOF {
 		o.updateSkipped(filter.nextSeq)
 	}
 
 	// set o.sseq to the first subject sequence
 	if filter.nextSeq > o.sseq {
 		o.sseq = filter.nextSeq
 	}
-	return nil, 0, lastErr
+	return nil, 0, err
 }
 
 // Will check for expiration and lack of interest on waiting requests.