Panic for invalid network type

cmd/harmony/main.go

@@ -146,6 +146,8 @@ func initSetup() {
 		config.Network = config.Testnet
 	case "devnet":
 		config.Network = config.Devnet
+	default:
+		panic(fmt.Sprintf("invalid network type: %s", *networkType))
 	}
 
 	// Set port and ip to global config.

common/config/global_config.go

@@ -10,5 +10,18 @@ const (
 	Devnet  NetworkType = 2
 )
 
+func (network NetworkType) String() string {
+	switch network {
+	case 0:
+		return "Mainnet"
+	case 1:
+		return "Testnet"
+	case 2:
+		return "Devnet"
+	default:
+		return "Unknown"
+	}
+}
+
 // Network is the type of Harmony network
 var Network = Testnet