protect against missing Ruby Marker

Change-Id: I04809443b5dc50904654936e608360b57c2e85c3
(cherry picked from commit 215516a5)
(cherry picked from commit 6c296afa)
Reviewed-on: https://gerrit.libreoffice.org/20584Reviewed-by: David Tardon <dtardon@redhat.com>
Tested-by: David Tardon <dtardon@redhat.com>
(cherry picked from commit d0bda255)

lotuswordpro/source/filter/lwpframelayout.cxx

@@ -1242,6 +1242,8 @@ void LwpRubyLayout::ConvertContentText()
 void LwpRubyLayout::RegisterStyle()
 {
     LwpRubyMarker* pMarker = GetMarker();
+    if (!pMarker)
+        throw std::runtime_error("missing Ruby Marker");
 
     XFRubyStyle* pRubyStyle = new XFRubyStyle;