Fix VM memory allocation optimizations by reducing what we allocate on the heap

internal/object/module.go

@@ -24,7 +24,7 @@ func (m Module) Inspect() string {
 	return fmt.Sprintf("<module '%s'>", m.Name)
 }
 
-func (m *Module) Get(index Object) (Object, error) {
+func (m Module) Get(index Object) (Object, error) {
 	key, ok := index.(Hashable)
 	if !ok {
 		return nil, fmt.Errorf("invalid module attribute %s", index.Type())
@@ -32,7 +32,7 @@ func (m *Module) Get(index Object) (Object, error) {
 
 	attr, found := m.Attrs.(*Hash).Pairs[key.HashKey()]
 	if !found {
-		return &Null{}, nil
+		return Null{}, nil
 	}
 
 	return attr.Value, nil