Decrease fragility in odd use cases with no current document (yet)

Especially, this happens when an Automation client wants to open a
Calc document. Equivalent to the code for the same situation in
getCurrentWordDoc().

Change-Id: I209a72dcae49f18cd265e0c6c2790618e1ebb4a1

vbahelper/source/vbahelper/vbahelper.cxx

@@ -262,7 +262,13 @@ getCurrentExcelDoc( const uno::Reference< uno::XComponentContext >& xContext )
     }
     catch (const uno::Exception&)
     {
-        xModel = getThisExcelDoc( xContext );
+        try
+        {
+            xModel = getThisExcelDoc( xContext );
+        }
+        catch (const uno::Exception&)
+        {
+        }
     }
     return xModel;
 }