Remove panic() and handle it appropriately (#5807)

This is an effort to remove panic from the source. 
Add a new call called CriticialIf, that calls LogIf and exits. 
Replace panics with one of CriticalIf, FatalIf and a return of error.

pkg/event/target/httpclient.go

@@ -19,7 +19,6 @@ package target
 import (
 	"encoding/json"
 	"errors"
-	"fmt"
 	"net/http"
 	"sync/atomic"
 	"time"
@@ -118,24 +117,28 @@ func (target *HTTPClientTarget) Close() error {
 	return nil
 }
 
-func mustGetNewUUID() string {
+func getNewUUID() (string, error) {
 	uuid, err := uuid.New()
 	if err != nil {
-		panic(fmt.Sprintf("%s. Unable to generate random UUID", err))
+		return "", err
 	}
 
-	return uuid.String()
+	return uuid.String(), nil
 }
 
 // NewHTTPClientTarget - creates new HTTP client target.
-func NewHTTPClientTarget(host xnet.Host, w http.ResponseWriter) *HTTPClientTarget {
+func NewHTTPClientTarget(host xnet.Host, w http.ResponseWriter) (*HTTPClientTarget, error) {
+	uuid, err := getNewUUID()
+	if err != nil {
+		return nil, err
+	}
 	c := &HTTPClientTarget{
-		id:      event.TargetID{"httpclient" + "+" + mustGetNewUUID() + "+" + host.Name, host.Port.String()},
+		id:      event.TargetID{"httpclient" + "+" + uuid + "+" + host.Name, host.Port.String()},
 		w:       w,
 		eventCh: make(chan []byte),
 		DoneCh:  make(chan struct{}),
 		stopCh:  make(chan struct{}),
 	}
 	c.start()
-	return c
+	return c, nil
 }

pkg/event/target/nats.go

@@ -112,7 +112,10 @@ func NewNATSTarget(id string, args NATSArgs) (*NATSTarget, error) {
 
 		clientID := args.Streaming.ClientID
 		if clientID == "" {
-			clientID = mustGetNewUUID()
+			clientID, err = getNewUUID()
+			if err != nil {
+				return nil, err
+			}
 		}
 
 		connOpts := []stan.Option{stan.NatsURL(addressURL)}