cmd: fix CLI package deprecation warnings

cmd/geth/chaincmd.go

@@ -72,7 +72,7 @@ Use "ethereum dump 0" to dump the genesis block.
 	}
 )
 
-func importChain(ctx *cli.Context) {
+func importChain(ctx *cli.Context) error {
 	if len(ctx.Args()) != 1 {
 		utils.Fatalf("This command requires an argument.")
 	}
@@ -84,9 +84,10 @@ func importChain(ctx *cli.Context) {
 		utils.Fatalf("Import error: %v", err)
 	}
 	fmt.Printf("Import done in %v", time.Since(start))
+	return nil
 }
 
-func exportChain(ctx *cli.Context) {
+func exportChain(ctx *cli.Context) error {
 	if len(ctx.Args()) < 1 {
 		utils.Fatalf("This command requires an argument.")
 	}
@@ -114,9 +115,10 @@ func exportChain(ctx *cli.Context) {
 		utils.Fatalf("Export error: %v\n", err)
 	}
 	fmt.Printf("Export done in %v", time.Since(start))
+	return nil
 }
 
-func removeDB(ctx *cli.Context) {
+func removeDB(ctx *cli.Context) error {
 	confirm, err := console.Stdin.PromptConfirm("Remove local database?")
 	if err != nil {
 		utils.Fatalf("%v", err)
@@ -132,9 +134,10 @@ func removeDB(ctx *cli.Context) {
 	} else {
 		fmt.Println("Operation aborted")
 	}
+	return nil
 }
 
-func upgradeDB(ctx *cli.Context) {
+func upgradeDB(ctx *cli.Context) error {
 	glog.Infoln("Upgrading blockchain database")
 
 	chain, chainDb := utils.MakeChain(ctx)
@@ -163,9 +166,10 @@ func upgradeDB(ctx *cli.Context) {
 		os.Remove(exportFile)
 		glog.Infoln("Import finished")
 	}
+	return nil
 }
 
-func dump(ctx *cli.Context) {
+func dump(ctx *cli.Context) error {
 	chain, chainDb := utils.MakeChain(ctx)
 	for _, arg := range ctx.Args() {
 		var block *types.Block
@@ -182,12 +186,12 @@ func dump(ctx *cli.Context) {
 			state, err := state.New(block.Root(), chainDb)
 			if err != nil {
 				utils.Fatalf("could not create new state: %v", err)
-				return
 			}
 			fmt.Printf("%s\n", state.Dump())
 		}
 	}
 	chainDb.Close()
+	return nil
 }
 
 // hashish returns true for strings that look like hashes.