fixes

frontend/models/Document.js

@@ -40,7 +40,6 @@ class Document extends BaseModel {
   views: number;
 
   data: Object;
-  fetchedAt: Date;
 
   /* Computed */
 
@@ -102,10 +101,6 @@ class Document extends BaseModel {
       : null;
   }
 
-  get timeSinceFetch(): number {
-    return (new Date() - this.fetchedAt) / 1000;
-  }
-
   /* Actions */
 
   @action star = async () => {
@@ -250,7 +245,6 @@ class Document extends BaseModel {
     if (dirty) this.hasPendingChanges = true;
     this.data = data;
     extendObservable(this, data);
-    this.fetchedAt = new Date();
   }
 
   constructor(data?: Object = {}) {