Made callback truly optional; made ERR() return the err

ERR.js

@@ -46,18 +46,12 @@ module.exports = function (err, callback)
       err = new Error(err);
     }
 
-    //there is a callback, lets call it
+    //if a callback is passed, lets call it
     if(callback != null)
     {
       callback(err);
     }
-    //no callback, throw the error
-    else
-    {
-      throw err;
-    }
   }
 
-  //return true if an error happend
-  return err != null;
+  return err;
 }

README.md

@@ -191,6 +191,6 @@ var ERR = require("async-stacktrace");
 The parameters of `ERR()` are: 
 
 1. `err` The error object (can be a string that describes the error too)
-2. `callback` (optional) If the callback is set and an error is passed, it will call the callback with the modified stacktrace. Else it will throw the error
+2. `callback` (optional) If the callback is set and an error is passed, it will call the callback with the modified stacktrace. Otherwise it will do nothing (the caller can pass the returned `err` object to the callback if desired).
 
-The return value is true if there is an error. Else its false
+The return value is the `err` object passed as the first parameter (if it was passed as a string, it will be returned as a first-class `Error()` object).

tests.js

@@ -20,13 +20,13 @@ vows.describe('ERR function').addBatch({
   }
 }).addBatch({
   'when you call it without an error' : {
-    'it returns false' : function() {
-      assert.isFalse(ERR());
+    'it returns falsy' : function() {
+      assert(!ERR());
     }
   },
   'when you call it with an error' : {
-    'it returns true' : function() {
-      assert.isTrue(ERR(new Error(), emptyFunc));
+    'it returns truthy' : function() {
+      assert(ERR(new Error(), emptyFunc));
     }
   },
   'when you give it a callback and an error': {
@@ -37,19 +37,11 @@ vows.describe('ERR function').addBatch({
     }
   },
   'when you give it no callback and an error': {
-    'it throws the error' : function() {
+    'it returns the error (so it can be passed to the callback)' : function() {
       var wasThrown = false;
 
-      try
-      {
-        ERR(new Error());
-      }
-      catch(e)
-      {
-        wasThrown = true;
-      }
-
-      assert.isTrue(wasThrown);
+      var err = new Error();
+      assert.equal(ERR(err), err);
     }
   },
   'when you call it with a string as an error' : {