cmd/swarm: remove shadow err (#17360)

cmd/swarm/config.go

@@ -132,7 +132,7 @@ func initSwarmNode(config *bzzapi.Config, stack *node.Node, ctx *cli.Context) {
 	log.Debug(printConfig(config))
 }
 
-//override the current config with whatever is in the config file, if a config file has been provided
+//configFileOverride overrides the current config with the config file, if a config file has been provided
 func configFileOverride(config *bzzapi.Config, ctx *cli.Context) (*bzzapi.Config, error) {
 	var err error
 
@@ -142,7 +142,8 @@ func configFileOverride(config *bzzapi.Config, ctx *cli.Context) (*bzzapi.Config
 		if filepath = ctx.GlobalString(SwarmTomlConfigPathFlag.Name); filepath == "" {
 			utils.Fatalf("Config file flag provided with invalid file path")
 		}
-		f, err := os.Open(filepath)
+		var f *os.File
+		f, err = os.Open(filepath)
 		if err != nil {
 			return nil, err
 		}