Fix nill/null value of IPList

Initialize IPList to an empty array if the IPList is nil/null.

jail.go

@@ -14,6 +14,11 @@ func jailGetHandler(res http.ResponseWriter, req *http.Request, fail2goConn *fai
 	useDNS, _ := fail2goConn.JailUseDNS(mux.Vars(req)["jail"])
 	maxRetry, _ := fail2goConn.JailMaxRetry(mux.Vars(req)["jail"])
 
+	//If IPList is nil/null/doesn't exist, then initialize it to an empty string array.  This resolves the front end issue where a null value is trying to be parsed for the ips.
+	if IPList == nil {
+		IPList = []string{}
+	}
+
 	encodedOutput, err := json.Marshal(map[string]interface{}{
 		"currentlyFailed": currentlyFailed,
 		"totalFailed":     totalFailed,