From 72ee74900c7683be287a4530cc70bfbd70e5ce9b Mon Sep 17 00:00:00 2001
From: Christian Henning <chhenning@sensentia.com>
Date: Fri, 5 Jan 2018 10:11:01 -0500
Subject: [PATCH] #31 if stream is bad then throw

---
 include/boost/gil/extension/io/detail/io_device.hpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/include/boost/gil/extension/io/detail/io_device.hpp b/include/boost/gil/extension/io/detail/io_device.hpp
index e8cf4e9a0..885afb946 100644
--- a/include/boost/gil/extension/io/detail/io_device.hpp
+++ b/include/boost/gil/extension/io/detail/io_device.hpp
@@ -354,7 +354,14 @@ class istream_device
 {
 public:
    istream_device( std::istream& in )
-   : _in( in ) {}
+   : _in( in )
+   {
+       if (!in)
+       {
+           // does the file exists?
+           io_error("Stream is not valid.");
+       }
+   }
 
     int getc_unchecked()
     {