From a7ba6afcbf958beb24588936d6209bb20dcb053c Mon Sep 17 00:00:00 2001
From: Jon Bodner <jon@bodnerfamily.com>
Date: Sat, 28 Nov 2020 23:56:55 -0500
Subject: [PATCH] improve error handling

---
 main.go | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/main.go b/main.go
index 6004542..5342791 100755
--- a/main.go
+++ b/main.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"log"
 	"os"
 
 	"github.com/learning-go-book/formatter"
@@ -9,8 +10,18 @@ import (
 )
 
 func main() {
-	amount, _ := decimal.NewFromString(os.Args[1])
-	percent, _ := decimal.NewFromString(os.Args[2])
+	if len(os.Args) < 3 {
+		fmt.Println("Need two parameters: amount and percent")
+		os.Exit(1)
+	}
+	amount, err := decimal.NewFromString(os.Args[1])
+	if err != nil {
+		log.Fatal(err)
+	}
+	percent, err := decimal.NewFromString(os.Args[2])
+	if err != nil {
+		log.Fatal(err)
+	}
 	percent = percent.Div(decimal.NewFromInt(100))
 	total := amount.Add(amount.Mul(percent)).Round(2)
 	fmt.Println(formatter.Space(80, os.Args[1], os.Args[2], total.StringFixed(2)))