tdf#120706: nullptr dereference

Change-Id: I55814a6b4cdfda93a51621b5b31c166507a7e7a6
Reviewed-on: https://gerrit.libreoffice.org/62005
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>
(cherry picked from commit 49d304c4)
Reviewed-on: https://gerrit.libreoffice.org/62028Reviewed-by: Eike Rathke <erack@redhat.com>

basic/source/runtime/dllmgr-x64.cxx

@@ -475,7 +475,7 @@ ErrCode call(
     OUString const & dll, ProcData const & proc, SbxArray * arguments,
     SbxVariable & result)
 {
-    if (arguments->Count() > 20)
+    if (arguments && arguments->Count() > 20)
         return ERRCODE_BASIC_NOT_IMPLEMENTED;
 
     std::vector< char > stack;