use jiracli.Error object to disambiguate between kingpin errors and cli errors

cmd/jira/main.go

@@ -329,11 +329,16 @@ func main() {
 		}
 	}
 	if _, err := app.Parse(os.Args[1:]); err != nil {
-		ctx, _ := app.ParseContext(os.Args[1:])
+		if _, ok := err.(*jiracli.Error); ok {
-		if ctx != nil {
+			log.Errorf("%s", err)
-			app.UsageForContext(ctx)
+			panic(jiracli.Exit{Code: 1})
+		} else {
+			ctx, _ := app.ParseContext(os.Args[1:])
+			if ctx != nil {
+				app.UsageForContext(ctx)
+			}
+			log.Errorf("Invalid Usage: %s", err)
+			panic(jiracli.Exit{Code: 1})
 		}
-		log.Errorf("Invalid Usage: %s", err)
-		panic(jiracli.Exit{Code: 1})
 	}
 }

jiracli/error.go

@@ -0,0 +1,13 @@
+package jiracli
+
+import "github.com/pkg/errors"
+
+type Error struct {
+	error
+}
+
+func cliError(cause error) error {
+	return &Error{
+		errors.WithStack(cause),
+	}
+}