[gnome-sound-recorder] fix crash on close app without record

[Bilal Elmoussaoui <bilelmoussaoui src gnome org>]

commit c9f308ccedf526c79fd209a2af464e8fb8988ef9
Author: Kavan Mevada <kavanmevada gmail com>
Date:   Sat Jun 6 11:47:13 2020 +0530

    fix crash on close app without record

 src/recorder.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/recorder.js b/src/recorder.js
index ae5b2d2..7489a64 100644
--- a/src/recorder.js
+++ b/src/recorder.js
@@ -151,7 +151,7 @@ var Recorder = new GObject.registerClass({
             this.recordBus = null;
         }
 
-        return new Recording(this.file);
+        return this.file ? new Recording(this.file) : null;
     }
 
     _onMessageReceived(message) {