Turn assert into SAL_WARN

In the wild there are named expressions without expression and
formula error cells without formula.

Change-Id: I11546b09173de65cebe776529edee74c549d73c8

sc/source/core/data/documen8.cxx

@@ -1195,7 +1195,10 @@ void ScDocument::CheckLinkFormulaNeedingCheck( const ScTokenArray& rCode )
     }
     else
     {
-        assert(!"called with empty ScTokenArray");
+        // Possible with named expression without expression like Excel
+        // internal print ranges, obscure user define names, ... formula error
+        // cells without formula ...
+        SAL_WARN("sc.core","ScDocument::CheckLinkFormulaNeedingCheck - called with empty ScTokenArray");
     }
 }