From c19fc266861d1e1c03204a340b5190d33722eedc Mon Sep 17 00:00:00 2001
From: Xuan Sang LE <xsang.le@gmail.com>
Date: Thu, 25 Jun 2020 14:56:07 +0200
Subject: [PATCH] Update BaseModel.ts

---
 src/core/BaseModel.ts | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/core/BaseModel.ts b/src/core/BaseModel.ts
index 6aa52ef..39ada1f 100644
--- a/src/core/BaseModel.ts
+++ b/src/core/BaseModel.ts
@@ -342,8 +342,11 @@ namespace OS {
             const evt = new BaseEvent("exit", force);
             this.onexit(evt);
             if (!evt.prevent) {
-                this.observable.off("*");
-                delete this._observable;
+                if(this.observable)
+                {
+                    this.observable.off("*");
+                    delete this._observable;
+                }
                 if (this.dialog) {
                     this.dialog.quit();
                 }