QSqlTableModel serious bug when preparing statement

The bug occurs in QSqlTableModelPrivate::exec().
When the prepared statement contains a NULL value for some field, for example :

   DELETE FROM aTable WHERE "id" = ? AND "field1" = ? AND "field2" IS NULL AND "field3" = ?

Then this leads to a SQL error like :

   ERROR: wrong number of parameters for prepared statement "qpsqlpstmt_1"
   DETAIL: Expected 3 parameters but got 4

The problem is located in qsqltablemodel.cpp, line 204 :

204  if (rec.isGenerated(i) && rec.value(i).type() != QVariant::Invalid)
205    editQuery.addBindValue(rec.value(i));

"rec.value( i )" can be a valid NULL QVariant (like QVariant(QVariant::Int)), and in this case line 205 is executed (which should not).