Fix reactivity systems not picking up when new properties are added

Author: tobyzerner

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+-   Fix reactivity systems not picking up when new properties are added
+
 ## [0.2.0-beta.8] - 2024-12-09
 
 ### Fixed

src/model.ts

@@ -55,6 +55,8 @@ class ModelBase<
                     return;
                 }
 
+                (this as any)[name] = null;
+
                 Object.defineProperty(this, name, {
                     get: () => this.attributes[name],
                     configurable: true,
@@ -80,6 +82,8 @@ class ModelBase<
                         return;
                     }
 
+                    (this as any)[name] = null;
+
                     Object.defineProperty(this, name, {
                         get: () => this.getRelationship(name),
                         configurable: true,