Stat image file to make sure it's present

main.go

@@ -21,6 +21,11 @@ type CliConfig struct {
 	OutputDir   *string
 }
 
+func checkImageFile(config *invoice.BillingConfig) error {
+	_, err := os.Stat(config.Business.ImageFile)
+	return err
+}
+
 func main() {
 	cli := CliConfig{
 		ConfigFile: kingpin.Flag("config-file", "The YAML config file to use").Short('c').Default("billing.yaml").String(),
@@ -56,6 +61,12 @@ func main() {
 		config.Business.SerifFont = serifFont
 	}
 
+	err = checkImageFile(config)
+	if err != nil {
+		println(err.Error())
+		os.Exit(1)
+	}
+
 	bill := invoice.NewBill(config)
 
 	err = bill.RenderToFile()