Check whether key passed with --name exists before redirecting to tx …

…create-validator

Closes: #2804

cmd/gaia/init/gentx.go

@@ -3,6 +3,7 @@ package init
 import (
 	"fmt"
 	"github.com/cosmos/cosmos-sdk/client"
+	"github.com/cosmos/cosmos-sdk/client/keys"
 	"github.com/cosmos/cosmos-sdk/cmd/gaia/app"
 	"github.com/cosmos/cosmos-sdk/codec"
 	"github.com/cosmos/cosmos-sdk/server"
@@ -61,6 +62,14 @@ following delegation and commission default parameters:
 				return err
 			}
 
+			kb, err := keys.GetKeyBaseFromDir(viper.GetString(flagClientHome))
+			if err != nil {
+				return err
+			}
+			if _, err = kb.Get(viper.GetString(client.FlagName)); err != nil {
+				return err
+			}
+
 			// Read --pubkey, if empty take it from priv_validator.json
 			if valPubKeyString := viper.GetString(cli.FlagPubKey); valPubKeyString != "" {
 				valPubKey, err = sdk.GetConsPubKeyBech32(valPubKeyString)