Merge pull request #1079 from Fenny/master

✏ fix typo

app.go

@@ -571,11 +571,11 @@ func (app *App) Listen(addr string) error {
 // ListenTLS serves HTTPs requests from the given addr.
 // certFile and keyFile are the paths to TLS certificate and key file.
 
-//  app.Listen(":8080", "./cert.pem", "./cert.key")
-//  app.Listen(":8080", "./cert.pem", "./cert.key")
+//  app.ListenTLS(":8080", "./cert.pem", "./cert.key")
+//  app.ListenTLS(":8080", "./cert.pem", "./cert.key")
 func (app *App) ListenTLS(addr, certFile, keyFile string) error {
 	// Check for valid cert/key path
-	if len(certFile) == 0 && len(keyFile) == 0 {
+	if len(certFile) == 0 || len(keyFile) == 0 {
 		return errors.New("tls: provide a valid cert or key path")
 	}
 	// Prefork is supported