Use standard exit status code for usage errors

* The stdlib `flags` package and most command line utilities use status code `2`.

1 files changed, 1 insertions, 1 deletions

diff --git a/parse.go b/parse.go
index 98c21cd..2bed8bf 100644
--- a/parse.go
+++ b/parse.go
@@ -90,7 +90,7 @@ func mustParse(config Config, dest ...interface{}) *Parser {
 	p, err := NewParser(config, dest...)
 	if err != nil {
 		fmt.Fprintln(config.Out, err)
-		config.Exit(-1)
+		config.Exit(2)
 		return nil
 	}