commit 65464349951e0df9b5d80c2eb3cc7458d54923ae
Author: David Faure <faure@kde.org>
Date:   Fri Oct 19 11:33:41 2012 +0200

    Fix crash when trying to reuse a frame with a null part.
    
    BUG: 271528
    FIXED-IN: 4.9.3

diff --git a/khtml/khtml_part.cpp b/khtml/khtml_part.cpp
index ad00ea5..6165710 100644
--- a/khtml/khtml_part.cpp
+++ b/khtml/khtml_part.cpp
@@ -5242,8 +5242,12 @@ KHTMLPart* KHTMLPartPrivate::top()
 
 bool KHTMLPartPrivate::canNavigate(KParts::ReadOnlyPart* bCand)
 {
+    if (!bCand) // No part here (e.g. invalid url), reuse that frame
+        return true;
+
     KHTMLPart* b = qobject_cast<KHTMLPart*>(bCand);
-    assert(b);
+    if (!b) // Another kind of part? Not sure what to do...
+        return false;
 
     // HTML5 gives conditions for this (a) being able to navigate b