From 4745f1fd648456f47e9824ae12178159d6ad007c Mon Sep 17 00:00:00 2001
From: Anthony Fok <foka@debian.org>
Date: Thu, 11 Dec 2014 10:06:11 -0700
Subject: [PATCH] In execute(), check if command is Runnable()

A corner case exists where c.Runnable() is not checked
before c.Run() is called, thus a nil c.Run is executed
leading to "panic: runtime error: invalid memory address
or nil pointer dereference".

This patch adds an extra c.Runnable() check in execute()
to catch that corner case.

Fixes #37.
---
 command.go | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/command.go b/command.go
index 7b2cf7de..2b289290 100644
--- a/command.go
+++ b/command.go
@@ -369,8 +369,9 @@ func (c *Command) execute(a []string) (err error) {
 		r.SetOutput(out)
 		return err
 	} else {
-		// If help is called, regardless of other flags, we print that
-		if c.helpFlagVal {
+		// If help is called, regardless of other flags, we print that.
+		// Print help also if c.Run is nil.
+		if c.helpFlagVal || !c.Runnable() {
 			c.Help()
 			return nil
 		}