commit b6196bc1fd489a5be69731ca9a19d8a95f721570
Author: Montel Laurent <montel@kde.org>
Date:   Thu Mar 12 07:48:15 2015 +0100

    Fix Bug 345071 - KMail crashed while I was reading an email
    
    BUG: 345071
    FIXED-IN: 4.16.7

diff --git a/kmail/kmmainwidget.cpp b/kmail/kmmainwidget.cpp
index 2228aef..92ba8c5 100644
--- a/kmail/kmmainwidget.cpp
+++ b/kmail/kmmainwidget.cpp
@@ -4498,5 +4498,6 @@ void KMMainWidget::populateMessageListStatusFilterCombo()
 
 void KMMainWidget::slotCollectionRemoved(const Akonadi::Collection &col)
 {
-    mFavoritesModel->removeCollection(col);
+    if (mFavoritesModel)
+       mFavoritesModel->removeCollection(col);
 }