From cde75530fed84f7236d41e196eef77b2820f32f6 Mon Sep 17 00:00:00 2001
From: James Turner <james@flightgear.org>
Date: Thu, 15 Jul 2021 08:43:31 +0100
Subject: [PATCH] =?UTF-8?q?BTG=20reading:=20don=E2=80=99t=20crash=20on=20e?=
 =?UTF-8?q?mpty=20error=20message?=
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Sentry-Id:FLIGHTGEAR-WA8
---
 simgear/io/lowlevel.cxx | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/simgear/io/lowlevel.cxx b/simgear/io/lowlevel.cxx
index 9ae5bb42..52852b57 100644
--- a/simgear/io/lowlevel.cxx
+++ b/simgear/io/lowlevel.cxx
@@ -48,9 +48,11 @@ static std::string gzErrorMessage(gzFile fd)
 
     if (errNum == Z_ERRNO) {
         return simgear::strutils::error_string(errno);
-    } else {
+    } else if (gzMsg) {
         return {gzMsg};
     }
+
+    return {"GZError: no string code for code:" + std::to_string(errNum)};
 }
 
 void sgReadChar ( gzFile fd, char *var )