Version:            (using Devel)
Installed from:    Compiled sources
OS:                Linux

I'm not sure why this assert is reached...
const KateTextLine::Ptr& KateLineLayout::textLine() const
{
  if (!m_textLine)
    m_textLine = m_doc->kateTextLine(line());

  Q_ASSERT(m_textLine);

  return m_textLine;
}

could be an unexpected null value returned... or is it caused by an error somewhere else?

Below is the stack trace:

Application: Kile (kile), signal SIGABRT
Using host libthread_db library "/lib/tls/i686/cmov/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread -1255844160 (LWP 11742)]
[New Thread -1285293168 (LWP 11744)]
[KCrash handler]
#6  0xffffe410 in __kernel_vsyscall ()
#7  0xb5cca875 in raise () from /lib/tls/i686/cmov/libc.so.6
#8  0xb5ccc201 in abort () from /lib/tls/i686/cmov/libc.so.6
#9  0xb7e6301d in qt_message_output () from /usr/lib/libQtCore.so.4
#10 0xb7e630a1 in qFatal () from /usr/lib/libQtCore.so.4
#11 0xb7e6320d in qt_assert () from /usr/lib/libQtCore.so.4
#12 0xb2d6d8c5 in KateLineLayout::textLine (this=0x8d94c90)
    at /home/hawk/stanzino/kde/src/4/KDE/kdelibs/kate/render/katelinelayout.cpp:68
#13 0xb2d6d931 in KateLineLayout::isValid (this=0x8d94c90)
    at /home/hawk/stanzino/kde/src/4/KDE/kdelibs/kate/render/katelinelayout.cpp:120
#14 0xb2d69406 in KateLayoutCache::line (this=0x8cc4c58, realLine=53, 
    virtualLine=53)
    at /home/hawk/stanzino/kde/src/4/KDE/kdelibs/kate/render/katelayoutcache.cpp:161
#15 0xb2d6a665 in KateLayoutCache::updateViewCache (this=0x8cc4c58, 
    startPos=@0x8cbef30, newViewLineCount=38, viewLinesScrolled=0)
    at /home/hawk/stanzino/kde/src/4/KDE/kdelibs/kate/render/katelayoutcache.cpp:148
#16 0xb2db63ed in KateViewInternal::doUpdateView (this=0x8cbee48, 
    changed=true, viewLinesScrolled=0)
    at /home/hawk/stanzino/kde/src/4/KDE/kdelibs/kate/view/kateviewinternal.cpp:560
#17 0xb2db6ce8 in KateViewInternal::updateView (this=0x8cbee48, changed=true, 
    viewLinesScrolled=0)
    at /home/hawk/stanzino/kde/src/4/KDE/kdelibs/kate/view/kateviewinternal.cpp:539
#18 0xb2dbb3ff in KateViewInternal::resizeEvent (this=0x8cbee48, e=0xbf8158c0)
    at /home/hawk/stanzino/kde/src/4/KDE/kdelibs/kate/view/kateviewinternal.cpp:2809
#19 0xb6f2e5e6 in QWidget::event () from /usr/lib/libQtGui.so.4
#20 0xb6edc44d in QApplicationPrivate::notify_helper ()
   from /usr/lib/libQtGui.so.4
#21 0xb6ede18a in QApplication::notify () from /usr/lib/libQtGui.so.4
#22 0xb7aad2cb in KApplication::notify (this=0xbf818efc, receiver=0x8cbee48, 
    event=0xbf8158c0)
    at /home/hawk/stanzino/kde/src/4/KDE/kdelibs/kdeui/kernel/kapplication.cpp:311
#23 0xb7f21456 in QCoreApplication::notifyInternal ()
   from /usr/lib/libQtCore.so.4
#24 0xb6ed917f in ?? () from /usr/lib/libQtGui.so.4
#25 0xbf818efc in ?? ()
#26 0x08cbee48 in ?? ()
#27 0xbf8158c0 in ?? ()
#28 0x0000027e in ?? ()
#29 0x00000000 in ?? ()
#0  0xffffe410 in __kernel_vsyscall ()