GUI: Fixed some GUI related start/stop crashes

git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@4223 8ced0084-cf51-0410-be5f-012b33b47a6e

Source/Plugins/Plugin_DSP_HLE/Src/UCodes/UCode_AX.cpp

@@ -157,6 +157,7 @@ if(m_DebuggerFrame->ScanMails)
 void CUCode_AX::SaveMail(bool Wii, u32 _uMail)
 {
 #if defined(HAVE_WX) && HAVE_WX
+if (!m_DebuggerFrame) return;
 if(m_DebuggerFrame->ScanMails)
 {
 	int i = 0;