remove node-zlib-backport as a dependency as it causes too many problems. Fixes #48

.travis.yml

@@ -1,7 +1,11 @@
 language: node_js
+before_script:
+  - test $TRAVIS_NODE_VERSION = '0.10' && npm i node-zlib-backport
+  - echo $TRAVIS_NODE_VERSION
 after_success:
-  - test $TRAVIS_NODE_VERSION = '4.3' && npm run coverage && npm install coveralls@2 && npm run coveralls
+  - test $TRAVIS_NODE_VERSION =~ 5.* && npm run coverage && npm i coveralls@2 && npm run coveralls
 node_js:
   - "0.10"
   - "0.12"
-  - "4.1"
+  - "4"
+  - "5"

appveyor.yml

@@ -4,7 +4,7 @@ clone_depth: 10
 
 environment:
   matrix:
-    - nodejs_version: '0.12'
+    - nodejs_version: '4'
     - nodejs_version: ''
 
 install:

lib/packer-sync.js

@@ -1,14 +1,25 @@
 'use strict';
 
+var hasSyncZlib = true;
 var zlib = require('zlib');
 if (!zlib.deflateSync) {
   // Backwards compatibility with 0.10.
-  zlib = require('node-zlib-backport');
+  try {
+    zlib = require('node-zlib-backport');
+  }
+  catch(ex) {
+    hasSyncZlib = false;
+  }
 }
 var constants = require('./constants');
 var Packer = require('./packer');
 
 module.exports = function(metaData, opt) {
+
+  if (!hasSyncZlib) {
+    throw new Error('To use the sync capability of this library in old node versions, please also add a dependency on node-zlb-backport');
+  }
+
   var options = opt || {};
 
   var packer = new Packer(options);

lib/parser-sync.js

@@ -1,9 +1,15 @@
 'use strict';
 
+var hasSyncZlib = true;
 var zlib = require('zlib');
-if (!zlib.inflateSync) {
+if (!zlib.deflateSync) {
   // Backwards compatibility with 0.10.
-  zlib = require('node-zlib-backport');
+  try {
+    zlib = require('node-zlib-backport');
+  }
+  catch(ex) {
+    hasSyncZlib = false;
+  }
 }
 var SyncReader = require('./sync-reader');
 var FilterSync = require('./filter-parse-sync');
@@ -14,6 +20,10 @@ var formatNormaliser = require('./format-normaliser');
 
 module.exports = function(buffer, options) {
 
+  if (!hasSyncZlib) {
+    throw new Error('To use the sync capability of this library in old node versions, please also add a dependency on node-zlb-backport');
+  }
+
   var err;
   function handleError(_err_) {
     err = _err_;
@@ -85,4 +95,3 @@ module.exports = function(buffer, options) {
 
   return metaData;
 };
-

package.json

@@ -1,6 +1,6 @@
 {
   "name": "pngjs",
-  "version": "2.3.0",
+  "version": "2.3.1",
   "description": "PNG encoder/decoder in pure JS, supporting any bit size & interlace, async & sync with full test suite.",
   "contributors": [
     "Alexandre Paré",
@@ -49,9 +49,6 @@
   "bugs": {
     "url": "https://github.com/lukeapage/pngjs2/issues"
   },
-  "optionalDependencies": {
-    "node-zlib-backport": "^0.11.15"
-  },
   "devDependencies": {
     "buffer-equal": "1.0.0",
     "connect": "^3.4.0",