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

internal/builtins/writefile.go

@@ -16,13 +16,13 @@ func WriteFile(args ...object.Object) object.Object {
 		return newError(err.Error())
 	}
 
-	filename := args[0].(*object.String).Value
-	data := []byte(args[1].(*object.String).Value)
+	filename := args[0].(object.String).Value
+	data := []byte(args[1].(object.String).Value)
 
 	err := os.WriteFile(filename, data, 0755)
 	if err != nil {
 		return newError("IOError: error writing file %s: %s", filename, err)
 	}
 
-	return &object.Null{}
+	return object.Null{}
 }