From e9834fedf1ac619c54cdc3b7be3f0a44a62d1e48 Mon Sep 17 00:00:00 2001
From: Hamar <david.hamar@timelinepi.com>
Date: Thu, 26 Jul 2018 14:51:17 +0200
Subject: [PATCH] Listen to stderr in toBuffer, so if the convert command fials
 we can return the error, instead of Error: Stream yields empty buffer

---
 lib/command.js | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/lib/command.js b/lib/command.js
index 2ff464fe..0a2aea9f 100644
--- a/lib/command.js
+++ b/lib/command.js
@@ -36,7 +36,7 @@ module.exports = function (proto) {
     }
   }
   
-  function streamToUnemptyBuffer(stream, callback) {
+  function streamToUnemptyBuffer(stream, callback, errorstream) {
     var done = false
     var buffers = []
 
@@ -44,6 +44,17 @@ module.exports = function (proto) {
       buffers.push(data)
     })
 
+    if (errorstream) {
+        errorstream.on('data', function (error) {
+          if (error) {
+              debug('Error stream data: ' + error.toString());
+              done = true;
+              buffers = null;
+              callback(error.toString());
+          }
+        });
+    }
+
     stream.on('end', function () {
       var result, err;
       if (done)
@@ -159,10 +170,10 @@ module.exports = function (proto) {
       throw new Error('gm().toBuffer() expects a callback.');
     }
 
-    return this.stream(format, function (err, stdout) {
+    return this.stream(format, function (err, stdout, stderr) {
       if (err) return callback(err);
 
-      streamToUnemptyBuffer(stdout, callback);
+      streamToUnemptyBuffer(stdout, callback, stderr);
     })
   }