From 5772588c29c906a7011ab6346aafcdf6e4a7f9d8 Mon Sep 17 00:00:00 2001
From: Audrius Butkevicius <audrius.butkevicius@gmail.com>
Date: Tue, 9 Sep 2014 23:56:44 +0100
Subject: [PATCH] Check if global discovery was actually started before trying
 to stop it (fixes #653)

---
 discover/discover.go | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/discover/discover.go b/discover/discover.go
index 9434aa66f..d508a7f08 100644
--- a/discover/discover.go
+++ b/discover/discover.go
@@ -108,8 +108,10 @@ func (d *Discoverer) StartGlobal(server string, extPort uint16) {
 }
 
 func (d *Discoverer) StopGlobal() {
-	close(d.stopGlobal)
-	d.globalWG.Wait()
+	if d.stopGlobal != nil {
+		close(d.stopGlobal)
+		d.globalWG.Wait()
+	}
 }
 
 func (d *Discoverer) ExtAnnounceOK() bool {