fix: Initials do not display on notification avatars (#5803)

app/models/Comment.ts

@@ -3,10 +3,11 @@ import { computed, observable } from "mobx";
 import { now } from "mobx-utils";
 import type { ProsemirrorData } from "@shared/types";
 import User from "~/models/User";
-import BaseModel from "./BaseModel";
+import Model from "./base/Model";
 import Field from "./decorators/Field";
+import Relation from "./decorators/Relation";
 
-class Comment extends BaseModel {
+class Comment extends Model {
   /**
    * Map to keep track of which users are currently typing a reply in this
    * comments thread.
@@ -40,18 +41,16 @@ class Comment extends BaseModel {
   @observable
   documentId: string;
 
-  createdAt: string;
-
+  @Relation(() => User)
   createdBy: User;
 
   createdById: string;
 
   resolvedAt: string;
 
+  @Relation(() => User)
   resolvedBy: User;
 
-  updatedAt: string;
-
   /**
    * An array of users that are currently typing a reply in this comments thread.
    */
@@ -60,7 +59,7 @@ class Comment extends BaseModel {
     return Array.from(this.typingUsers.entries())
       .filter(([, lastReceivedDate]) => lastReceivedDate > subSeconds(now(), 3))
       .map(([userId]) => this.store.rootStore.users.get(userId))
-      .filter(Boolean);
+      .filter(Boolean) as User[];
   }
 }