From d543ba965610927566b2921d810aa51004827a7d Mon Sep 17 00:00:00 2001
From: Alexander Skvortsov <sasha.skvortsov109@gmail.com>
Date: Mon, 13 Dec 2021 12:34:51 -0500
Subject: [PATCH 1/2] Make sure `this.data.attributes` is initialized.

`Object.assign` is not type-safe, and does ensure that the property being assigned to is not undefined.
---
 framework/core/js/src/common/Model.ts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/framework/core/js/src/common/Model.ts b/framework/core/js/src/common/Model.ts
index 9cea14335..338b66207 100644
--- a/framework/core/js/src/common/Model.ts
+++ b/framework/core/js/src/common/Model.ts
@@ -110,6 +110,7 @@ export default abstract class Model {
     }
 
     if ('attributes' in data) {
+      this.data.attributes ||= {};
       Object.assign(this.data.attributes, data.attributes);
     }
 

From d494a6a7d078945d863dc31ae29e69b7099d26f0 Mon Sep 17 00:00:00 2001
From: Alexander Skvortsov <sasha.skvortsov109@gmail.com>
Date: Mon, 13 Dec 2021 15:07:30 -0500
Subject: [PATCH 2/2] Don't throw errors for undefined relationships

---
 framework/core/js/src/common/Model.ts | 28 ++++++++++++---------------
 1 file changed, 12 insertions(+), 16 deletions(-)

diff --git a/framework/core/js/src/common/Model.ts b/framework/core/js/src/common/Model.ts
index 338b66207..1bc29431e 100644
--- a/framework/core/js/src/common/Model.ts
+++ b/framework/core/js/src/common/Model.ts
@@ -296,16 +296,14 @@ export default abstract class Model {
   static hasOne<M extends Model | null>(name: string): () => M | null | false;
   static hasOne<M extends Model>(name: string): () => M | false {
     return function (this: Model) {
-      if (this.data.relationships) {
-        const relationshipData = this.data.relationships[name]?.data;
+      const relationshipData = this.data.relationships?.[name]?.data;
 
-        if (relationshipData instanceof Array) {
-          throw new Error(`Relationship ${name} on model ${this.data.type} is plural, so the hasOne method cannot be used to access it.`);
-        }
+      if (relationshipData && relationshipData instanceof Array) {
+        throw new Error(`Relationship ${name} on model ${this.data.type} is plural, so the hasOne method cannot be used to access it.`);
+      }
 
-        if (relationshipData) {
-          return this.store.getById<M>(relationshipData.type, relationshipData.id) as M;
-        }
+      if (relationshipData) {
+        return this.store.getById<M>(relationshipData.type, relationshipData.id) as M;
       }
 
       return false;
@@ -322,16 +320,14 @@ export default abstract class Model {
    */
   static hasMany<M extends Model>(name: string): () => (M | undefined)[] | false {
     return function (this: Model) {
-      if (this.data.relationships) {
-        const relationshipData = this.data.relationships[name]?.data;
+      const relationshipData = this.data.relationships?.[name]?.data;
 
-        if (!(relationshipData instanceof Array)) {
-          throw new Error(`Relationship ${name} on model ${this.data.type} is singular, so the hasMany method cannot be used to access it.`);
-        }
+      if (relationshipData && !(relationshipData instanceof Array)) {
+        throw new Error(`Relationship ${name} on model ${this.data.type} is singular, so the hasMany method cannot be used to access it.`);
+      }
 
-        if (relationshipData) {
-          return relationshipData.map((data) => this.store.getById<M>(data.type, data.id));
-        }
+      if (relationshipData) {
+        return relationshipData.map((data) => this.store.getById<M>(data.type, data.id));
       }
 
       return false;