OfType with a where clause fails with a NotSupportedException

Stack trace is:
System.NotSupportedException : Specified method is not supported.
at NHibernate.Hql.Ast.ANTLR.PolymorphicQuerySourceDetector.GetClassName(IASTNode querySource) in d:\Source\NHibernate\nhibernate\src\NHibernate\Hql\Ast\ANTLR\PolymorphicQuerySourceDetector.cs: line 61
at NHibernate.Hql.Ast.ANTLR.PolymorphicQuerySourceDetector.Process(IASTNode tree) in d:\Source\NHibernate\nhibernate\src\NHibernate\Hql\Ast\ANTLR\PolymorphicQuerySourceDetector.cs: line 27
at NHibernate.Hql.Ast.ANTLR.AstPolymorphicProcessor.Process() in d:\Source\NHibernate\nhibernate\src\NHibernate\Hql\Ast\ANTLR\AstPolymorphicProcessor.cs: line 30
at NHibernate.Hql.Ast.ANTLR.ASTQueryTranslatorFactory.CreateQueryTranslators(IASTNode ast, String queryIdentifier, String collectionRole, Boolean shallow, IDictionary`2 filters, ISessionFactoryImplementor factory) in d:\Source\NHibernate\nhibernate\src\NHibernate\Hql\Ast\ANTLR\ASTQueryTranslatorFactory.cs: line 35
at NHibernate.Hql.Ast.ANTLR.ASTQueryTranslatorFactory.CreateQueryTranslators(String queryIdentifier, IQueryExpression queryExpression, String collectionRole, Boolean shallow, IDictionary`2 filters, ISessionFactoryImplementor factory) in d:\Source\NHibernate\nhibernate\src\NHibernate\Hql\Ast\ANTLR\ASTQueryTranslatorFactory.cs: line 27
at NHibernate.Engine.Query.HQLExpressionQueryPlan..ctor(String expressionStr, IQueryExpression queryExpression, String collectionRole, Boolean shallow, IDictionary`2 enabledFilters, ISessionFactoryImplementor factory) in d:\Source\NHibernate\nhibernate\src\NHibernate\Engine\Query\HQLExpressionQueryPlan.cs: line 27
at NHibernate.Engine.Query.HQLExpressionQueryPlan..ctor(String expressionStr, IQueryExpression queryExpression, Boolean shallow, IDictionary`2 enabledFilters, ISessionFactoryImplementor factory) in d:\Source\NHibernate\nhibernate\src\NHibernate\Engine\Query\HQLExpressionQueryPlan.cs: line 17
at NHibernate.Engine.Query.QueryPlanCache.GetHQLQueryPlan(IQueryExpression queryExpression, Boolean shallow, IDictionary`2 enabledFilters) in d:\Source\NHibernate\nhibernate\src\NHibernate\Engine\Query\QueryPlanCache.cs: line 89
at NHibernate.Impl.AbstractSessionImpl.GetHQLQueryPlan(IQueryExpression queryExpression, Boolean shallow) in d:\Source\NHibernate\nhibernate\src\NHibernate\Impl\AbstractSessionImpl.cs: line 302
at NHibernate.Impl.AbstractSessionImpl.CreateQuery(IQueryExpression queryExpression) in d:\Source\NHibernate\nhibernate\src\NHibernate\Impl\AbstractSessionImpl.cs: line 258
at NHibernate.Linq.NhQueryProvider.Execute(Expression expression) in d:\Source\NHibernate\nhibernate\src\NHibernate\Linq\NhQueryProvider.cs: line 24
at NHibernate.Linq.NhQueryProvider.Execute(Expression expression) in d:\Source\NHibernate\nhibernate\src\NHibernate\Linq\NhQueryProvider.cs: line 55
at Remotion.Data.Linq.QueryableBase`1.GetEnumerator()
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
at System.Linq.Enumerable.ToList(IEnumerable`1 source)
at Tests.LinqTests.OfType() in LinqTests.cs: line 55

LINQ query is:

(from p
in this.Session.Query<Animal>().OfType<Crocodile>()
where p.TeethCount == 1
select p).ToList();

This is clearly not a sensible thing to do but it demonstrates the bug quite nicely.

If the where clause is excluded the query runs OK.

Both queries are in attached unit test against SQLite