Initialize wxLogWindow::m_pLogFrame in ctor to avoid (rare) crash.

If the log frame creation itself generates log messages, the code using
wxLogWindow could crash because its m_pLogFrame member variable wasn't
initialized yet at this moment.

Do set it to NULL initially now to avoid this.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66383 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/logg.cpp

@@ -610,6 +610,11 @@ wxLogWindow::wxLogWindow(wxWindow *pParent,
                          bool bShow,
                          bool bDoPass)
 {
+    // Initialize it to NULL to ensure that we don't crash if any log messages
+    // are generated before the frame is fully created (while this doesn't
+    // happen normally, it might, in principle).
+    m_pLogFrame = NULL;
+
     PassMessages(bDoPass);
 
     m_pLogFrame = new wxLogFrame(pParent, this, szTitle);