Ensured properties cannot be overridden with methods

lib/util.js

@@ -228,7 +228,9 @@ exports.propCopy = function( props, dest, result_data )
                 }
                 else
                 {
-                    // todo: attempted override of property with method
+                    throw new Error(
+                        "Cannot override property '" + name + "' with method"
+                    );
                 }
 
                 if ( data.abstractModified )

test/test-class-extend.js

@@ -126,3 +126,12 @@ assert.notEqual(
     "Subtype should contain extended members"
 );
 
+
+assert.throws( function()
+{
+    Class.extend( OtherClass,
+    {
+        foo: function() {},
+    });
+}, Error, "Cannot override property with a method" );
+