[FAB-5141] configtxgen --version should not panic

If configtxgen cannot find a configtx.yaml file,
it panics.  While this in and of itself is ok,
it should not panic when simply trying to get the
version.

Two changes were made:

- move response to --version above all other flags
- added a defer / recover function to better handle
config not found and make things more clear

Change-Id: I512d1fed464c734db7178eb576440c45767f6994
Signed-off-by: Gari Singh <gari.r.singh@gmail.com>

Author: mastersingh24

common/configtx/tool/configtxgen/main.go

@@ -23,6 +23,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"strings"
 
 	"github.com/hyperledger/fabric/bccsp/factory"
 	"github.com/hyperledger/fabric/common/config"
@@ -347,17 +348,30 @@ func main() {
 
 	flag.Parse()
 
+	// show version
+	if *version {
+		printVersion()
+		os.Exit(exitCode)
+	}
+
 	logging.SetLevel(logging.INFO, "")
 
+	// don't need to panic when running via command line
+	defer func() {
+		if err := recover(); err != nil {
+			if strings.Contains(fmt.Sprint(err), "Error reading configuration: Unsupported Config Type") {
+				logger.Error("Could not find configtx.yaml. " +
+					"Please make sure that FABRIC_CFG_PATH is set to a path " +
+					"which contains configtx.yaml")
+			}
+			os.Exit(1)
+		}
+	}()
+
 	logger.Info("Loading configuration")
 	factory.InitFactories(nil)
 	config := genesisconfig.Load(profile)
 
-	if *version {
-		printVersion()
-		os.Exit(exitCode)
-	}
-
 	if outputBlock != "" {
 		if err := doOutputBlock(config, channelID, outputBlock); err != nil {
 			logger.Fatalf("Error on outputBlock: %s", err)