From f8536b74464f7913e0b64df74351781aa11f359d Mon Sep 17 00:00:00 2001
From: Jerko Steiner <jerko.steiner@gmail.com>
Date: Wed, 14 Aug 2019 14:16:19 +0700
Subject: [PATCH] Make flag error message more helpful when flag undefined

---
 packages/argparse/src/argparse.ts | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/packages/argparse/src/argparse.ts b/packages/argparse/src/argparse.ts
index 914de2f..be9596c 100644
--- a/packages/argparse/src/argparse.ts
+++ b/packages/argparse/src/argparse.ts
@@ -310,7 +310,9 @@ export function argparse<T extends IArgsConfig>(
       }, {} as Record<string, true>)
 
       function getArgumentName(nameOrAlias: string): string {
-        return nameOrAlias in config ? nameOrAlias : aliases[nameOrAlias]
+        return (nameOrAlias in config
+          ? nameOrAlias
+          : aliases[nameOrAlias]) || nameOrAlias
       }
 
       function processFlags(argument: string): string {