Fix previously not supported test

Author: maca88

src/NHibernate.Test/Async/NHSpecificTest/GH1879/FixtureByCode.cs

@@ -12,6 +12,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using NHibernate.Cfg.MappingSchema;
+using NHibernate.Exceptions;
 using NHibernate.Mapping.ByCode;
 using NHibernate.Type;
 using NUnit.Framework;
@@ -124,8 +125,7 @@ protected async Task AreEqualAsync<TResult>(
 				{
 					expectedResult = await (expectedQuery(session.Query<T>()).ToListAsync(cancellationToken));
 				}
-				catch (OperationCanceledException) { throw; }
-				catch (Exception e)
+				catch (GenericADOException e)
 				{
 					Assert.Ignore($"Not currently supported query: {e}");
 				}

src/NHibernate.Test/NHSpecificTest/GH1879/FixtureByCode.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using NHibernate.Cfg.MappingSchema;
+using NHibernate.Exceptions;
 using NHibernate.Mapping.ByCode;
 using NHibernate.Type;
 using NUnit.Framework;
@@ -111,7 +112,7 @@ protected void AreEqual<TResult>(
 				{
 					expectedResult = expectedQuery(session.Query<T>()).ToList();
 				}
-				catch (Exception e)
+				catch (GenericADOException e)
 				{
 					Assert.Ignore($"Not currently supported query: {e}");
 				}

src/NHibernate/Linq/ReWriters/ConditionalQueryReferenceExpander.cs

@@ -31,6 +31,14 @@ public override void VisitSelectClause(SelectClause selectClause, QueryModel que
 			_expander.Transform(selectClause);
 		}
 
+		public override void VisitMainFromClause(MainFromClause fromClause, QueryModel queryModel)
+		{
+			if (fromClause.FromExpression is SubQueryExpression subqueryExpression)
+			{
+				VisitQueryModel(subqueryExpression.QueryModel);
+			}
+		}
+
 		public override void VisitOrdering(Ordering ordering, QueryModel queryModel, OrderByClause orderByClause, int index)
 		{
 			_expander.Transform(ordering);

src/NHibernate/Linq/ReWriters/SubQueryConditionalExpander.cs

@@ -24,6 +24,14 @@ public override void VisitSelectClause(SelectClause selectClause, QueryModel que
 			_expander.Transform(selectClause);
 		}
 
+		public override void VisitMainFromClause(MainFromClause fromClause, QueryModel queryModel)
+		{
+			if (fromClause.FromExpression is SubQueryExpression subqueryExpression)
+			{
+				VisitQueryModel(subqueryExpression.QueryModel);
+			}
+		}
+
 		public override void VisitOrdering(Ordering ordering, QueryModel queryModel, OrderByClause orderByClause, int index)
 		{
 			_expander.Transform(ordering);