Prefer cmd arg over env

cmd/rbxcompiler/rbxcompiler.go

@@ -50,20 +50,13 @@ func build() {
 
 	if *doUpload {
 		rbxcookie := os.Getenv("RBXCOOKIE")
-		if rbxcookie == "" {
-			if cookieFile == nil {
-				fmt.Printf("No credentials provided\n")
-				os.Exit(1)
-				return
-			}
-
+		if *cookieFile != "" {
 			data, err := os.ReadFile(*cookieFile)
 			if err != nil {
 				fmt.Printf("Failed read cookie file: %s\n", err)
 				os.Exit(1)
 				return
 			}
-
 			rbxcookie = strings.Replace(string(data), "\n", "", -1)
 		}