Apply "errorfirst" convention

Author: Axel Rindle

examples/callback.js

@@ -12,7 +12,7 @@ const options = {
   currentVersion: require('../package.json').version
 };
 
-versionCheck(options, function (update, error) {
+versionCheck(options, function (error, update) {
   if (error) {
     console.error(error);
     process.exit(-1);

examples/tags.js

@@ -13,7 +13,7 @@ const options = {
   fetchTags: true
 };
 
-versionCheck(options, function (update, error) {
+versionCheck(options, function (error, update) {
   if (error) {
     console.error(error);
     process.exit(-1);

lib/main.coffee

@@ -40,18 +40,18 @@ check = (options, callback) ->
   fetchTags = options.fetchTags || false
 
   # check if required options are defined
-  callback(null, 'no token specified') if token is undefined
-  callback(null, 'no repository specified') if repo is undefined
-  callback(null, 'no owner specified') if owner is undefined
-  callback(null, 'no current version given') if currentVersion is undefined
+  callback('no token specified', null) if token is undefined
+  callback('no repository specified', null) if repo is undefined
+  callback('no owner specified', null) if owner is undefined
+  callback('no current version given', null) if currentVersion is undefined
 
   # build the query
   query = if fetchTags then query.tags repo, owner else query.releases repo, owner
 
   # do the api call
   graphql (token: token, query: query), (err, res) ->
     if err
-      callback null, err
+      callback err, null
     else
       # Retrieve newer version name
       newer =
@@ -62,7 +62,7 @@ check = (options, callback) ->
 
       # Compare versions
       if semver.gt (if fetchTags then newer.name else newer.tag.name), currentVersion
-        callback newer, null
+        callback null, newer
       else
         callback null, null