chore: upgrade dependencies

vendor/github.com/eclipse/paho.mqtt.golang/filestore.go

@@ -1,10 +1,14 @@
 /*
- * Copyright (c) 2013 IBM Corp.
+ * Copyright (c) 2021 IBM Corp and others.
  *
  * All rights reserved. This program and the accompanying materials
- * are made available under the terms of the Eclipse Public License v1.0
- * which accompanies this distribution, and is available at
- * http://www.eclipse.org/legal/epl-v10.html
+ * are made available under the terms of the Eclipse Public License v2.0
+ * and Eclipse Distribution License v1.0 which accompany this distribution.
+ *
+ * The Eclipse Public License is available at
+ *    https://www.eclipse.org/legal/epl-2.0/
+ * and the Eclipse Distribution License is available at
+ *   http://www.eclipse.org/org/documents/edl-v10.php.
  *
  * Contributors:
  *    Seth Hoenig
@@ -168,7 +172,7 @@ func (store *FileStore) all() []string {
 	for _, f := range files {
 		DEBUG.Println(STR, "file in All():", f.Name())
 		name := f.Name()
-		if name[len(name)-4:] != msgExt {
+		if len(name) < len(msgExt) || name[len(name)-len(msgExt):] != msgExt {
 			DEBUG.Println(STR, "skipping file, doesn't have right extension: ", name)
 			continue
 		}