Methods can no longer be overridden with non-methods (anything other than a Function)

lib/class.js

@@ -73,6 +73,7 @@ function prop_copy( props, dest )
         // care about methods - properties will simply have their values
         // overwritten)
         var pre    = dest[ property ],
+            prop   = props[ property ],
             getter = ( ( getset ) ? props.__lookupGetter__( property ) : null ),
             setter = ( ( getset ) ? props.__lookupSetter__( property ) : null );
 
@@ -92,6 +93,12 @@ function prop_copy( props, dest )
         // check for method overrides
         else if ( ( pre !== undefined ) && ( pre instanceof Function ) )
         {
+            // ensure we're overriding the method with another method
+            if ( !( prop instanceof Function ) )
+            {
+                throw new TypeError( "Cannot override method with non-method" );
+            }
+
             dest[ property ] = ( function( method, super_method )
             {
                 // this is the method that will be invoked when the requested
@@ -109,11 +116,11 @@ function prop_copy( props, dest )
 
                     return retval;
                 }
-            })( props[ property ], dest[ property ] );
+            })( prop, dest[ property ] );
         }
         else
         {
-            dest[ property ] = props[ property ];
+            dest[ property ] = prop;
         }
     }
 }

test/test-class-parent.js

@@ -118,3 +118,12 @@ assert.equal(
     "The parent property may also be used to invoke parent methods"
 );
 
+assert.throws( function()
+{
+    Foo.extend(
+    {
+        // overriding method with scalar; shouldn't be allowed
+        myMethod: 'scalar',
+    });
+}, TypeError, "Methods must be overridden with a Function" );
+