Avoid a SolarMutex assertion failure in some use cases from Automation

For instance when opening a Calc Document through ooo::vba::excel::
XWorkbooks::Open(). Instead just let the function return null. It does
seem that callers are prepared for that.

Change-Id: I7136133155f95a696b5ed3e661a9adb98396c9c5

vbahelper/source/vbahelper/vbahelper.cxx

-/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column:100 -*- */
 /*
  * This file is part of the LibreOffice project.
  *
@@ -39,6 +39,7 @@
 
 #include <ooo/vba/msforms/XShape.hpp>
 
+#include <comphelper/automationinvokedzone.hxx>
 #include <comphelper/processfactory.hxx>
 
 #include <sfx2/objsh.hxx>
@@ -1122,6 +1123,12 @@ uno::Reference< XHelperInterface > getUnoDocModule( const OUString& aModName, Sf
     if ( pShell )
     {
         OUString sProj( "Standard" );
+        // GetBasicManager() causes a SolarMutex assertion failure in some use cases from
+        // Automation, at least when opening a Calc Document through ooo::vba::excel::
+        // XWorkbooks::Open(). Let's see if this check is a good way around that. It does seem that
+        // callers are prepared for this to return null?
+        if (comphelper::Automation::AutomationInvokedZone::isActive())
+            return xIf;
         BasicManager* pBasMgr = pShell->GetBasicManager();
         if ( pBasMgr && !pBasMgr->GetName().isEmpty() )
             sProj = pBasMgr->GetName();