Check arguments length before reading

fix

```
panic: runtime error: index out of range [1] with length 1

goroutine 1 [running]:
main.getQuestion()
        /build/dnslookup/parts/dnslookup/build/main.go:239 +0x147
main.main()
        /build/dnslookup/parts/dnslookup/build/main.go:44 +0x145
```

main.go

@@ -39,6 +39,13 @@ func main() {
 	verbose := os.Getenv("VERBOSE") == "1"
 	padding := os.Getenv("PAD") == "1"
 	do := os.Getenv("DNSSEC") == "1"
+
+	if len(os.Args) != 2 && len(os.Args) != 3 && len(os.Args) != 4 && len(os.Args) != 5 {
+		log.Printf("Wrong number of arguments")
+		usage()
+		os.Exit(1)
+	}
+
 	subnetOpt := getSubnet()
 	ednsOpt := getEDNSOpt()
 	question := getQuestion()
@@ -66,12 +73,6 @@ func main() {
 		os.Exit(0)
 	}
 
-	if len(os.Args) != 2 && len(os.Args) != 3 && len(os.Args) != 4 && len(os.Args) != 5 {
-		log.Printf("Wrong number of arguments")
-		usage()
-		os.Exit(1)
-	}
-
 	if timeoutStr != "" {
 		i, err := strconv.Atoi(timeoutStr)
 		if err != nil {