ofz#7043 already registered

Change-Id: Ic94891c82944d04fe3391c0bd0731a6e3e4373e0
Reviewed-on: https://gerrit.libreoffice.org/51693Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>

lotuswordpro/source/filter/lwpfrib.cxx

@@ -451,6 +451,8 @@ XFColor LwpFrib::GetHighlightColor()
 
 void LwpFrib::Register(std::map<LwpFrib*,OUString>* pFribMap)
 {
+    if (m_pFribMap)
+        throw std::runtime_error("registered already");
     m_pFribMap = pFribMap;
 }