Crash into QTextEdit::setHtml()

I have experiment some crash with QTextEdit::setHtml() under linux and windows, the backtrace:
QtCored4.dll!qt_message_output(QtMsgType msgType=QtFatalMsg, const char * buf=0x0000000003f8b018) Line 2013 C++
QtCored4.dll!qFatal(const char * msg=0x00000000672d02c8, ...) Line 2216 + 0x35 bytes C++
QtCored4.dll!qt_assert_x(const char * where=0x0000000067341088, const char * what=0x000000000404d0e8, const char * file=0x0000000067340fe0, int line=305) Line 1795 C++
> QtCored4.dll!QCoreApplicationPrivate::checkReceiverThread(QObject * receiver=0x0000000003bb7870) Line 305 + 0x385 bytes C++
QtGuid4.dll!QApplication::notify(QObject * receiver=0x0000000003bb7870, QEvent * e=0x0000000004c2d278) Line 3548 C++
QtCored4.dll!QCoreApplication::notifyInternal(QObject * receiver=0x0000000003bb7870, QEvent * event=0x0000000004c2d278) Line 610 + 0x26 bytes C++
QtCored4.dll!QCoreApplication::sendEvent(QObject * receiver=0x0000000003bb7870, QEvent * event=0x0000000004c2d278) Line 213 + 0x50 bytes C++
QtCored4.dll!QObjectPrivate::setParent_helper(QObject * o=0x0000000000000000) Line 1871 + 0x16 bytes C++
QtCored4.dll!QObject::~QObject() Line 856 C++
QtGuid4.dll!QTextObject::~QTextObject() Line 113 + 0xb bytes C++
QtGuid4.dll!QTextFrame::~QTextFrame() Line 430 + 0xa bytes C++
QtGuid4.dll!QTextFrame::`vector deleting destructor'() + 0x65 bytes C++
QtGuid4.dll!QTextDocumentPrivate::clear() Line 261 + 0x4d bytes C++
QtGuid4.dll!QTextDocument::setHtml(const QString & html="<pre><span style="color: #94a5ff;"><b>(<span style="color: white;">____</span>391)</b> main.cpp:709:<span style="color: white;">________</span> <i><u>Infos()</u></i>: Msvc version: 150021022</spa) Line 1127 C++
QtGuid4.dll!QTextControlPrivate::setContent(Qt::TextFormat format=RichText, const QString & text="<pre><span style="color: #94a5ff;"><b>(<span style="color: white;">____</span>391)</b> main.cpp:709:<span style="color: white;">________</span> <i><u>Infos()</u></i>: Msvc version: 150021022</spa, QTextDocument * document=0x0000000000000000) Line 473 C++
QtGuid4.dll!QTextControl::setHtml(const QString & text="<pre><span style="color: #94a5ff;"><b>(<span style="color: white;">____</span>391)</b> main.cpp:709:<span style="color: white;">________</span> <i><u>Infos()</u></i>: Msvc version: 150021022</spa) Line 1122 C++
QtGuid4.dll!QTextEdit::setHtml(const QString & text="<pre><span style="color: #94a5ff;"><b>(<span style="color: white;">____</span>391)</b> main.cpp:709:<span style="color: white;">________</span> <i><u>Infos()</u></i>: Msvc version: 150021022</spa) Line 1160 C++
ultracopier.exe!helpDialog::new_html_log(QString * theNewHtml="<span style="color: #94a5ff;"><b>(<span style="color: white;">__</span>61805)</b> AddFolder.cpp:70:<span style="color: white;">____</span> <i><u>AddFolderThread::run()</u></i>: start</span>
") Line 41 + 0xaf bytes C++
ultracopier.exe!UIcon::appendLog(QString * htmlFormat="<span style="color: #94a5ff;"><b>(<span style="color: white;">__</span>61805)</b> AddFolder.cpp:70:<span style="color: white;">____</span> <i><u>AddFolderThread::run()</u></i>: start</span>
") Line 235 + 0x35 bytes C++
ultracopier.exe!debug_console_fonction(int number=30, const QString & fonction="AddFolderThread::run", const QString & text="start", QString * file="AddFolder.cpp", const int & ligne=70) Line 1042 C++
ultracopier.exe!AddFolderThread::run() Line 70 + 0x78 bytes C++
QtCored4.dll!QThreadPrivate::start(void * arg=0x0000000003a4ba00) Line 310 C++
msvcr90d.dll!_callthreadstartex() Line 348 + 0x17 bytes C
msvcr90d.dll!_threadstartex(void * ptd=0x0000000004065bf0) Line 331 C
kernel32.dll!000000007708542d()
[Frames below may be incorrect and/or missing, no symbols loaded for kernel32.dll]
ntdll.dll!00000000771cbe51()
Thanks to fix it.