Appears "Object reference not set to an instance of an object.
   at MongoDB.Bson.Serialization.Serializers.Int32Serializer.Serialize(BsonWriter bsonWriter, Type nominalType, Object value, IBsonSerializationOptions options)
   at MongoDB.Bson.Serialization.BsonSerializationInfo.SerializeValue(Object value)
   at MongoDB.Driver.Linq.PredicateTranslator.BuildComparisonQuery(Expression variableExpression, ExpressionType operatorType, ConstantExpression constantExpression)
   at MongoDB.Driver.Linq.PredicateTranslator.BuildQuery(Expression expression)
   at MongoDB.Driver.Linq.PredicateTranslator.BuildQuery(Expression expression)
   at MongoDB.Driver.Linq.PredicateTranslator.BuildOrElseQuery(BinaryExpression binaryExpression)
   at MongoDB.Driver.Linq.PredicateTranslator.BuildQuery(Expression expression)
   at MongoDB.Driver.Linq.PredicateTranslator.BuildOrElseQuery(BinaryExpression binaryExpression)
   at MongoDB.Driver.Linq.PredicateTranslator.BuildQuery(Expression expression)
   at MongoDB.Driver.Linq.PredicateTranslator.BuildOrElseQuery(BinaryExpression binaryExpression)
   at MongoDB.Driver.Linq.PredicateTranslator.BuildQuery(Expression expression)
   at MongoDB.Driver.Linq.PredicateTranslator.BuildQuery(Expression expression)
   at MongoDB.Driver.Linq.PredicateTranslator.BuildAnyQuery(MethodCallExpression methodCallExpression)
   at MongoDB.Driver.Linq.PredicateTranslator.BuildMethodCallQuery(MethodCallExpression methodCallExpression)
   at MongoDB.Driver.Linq.PredicateTranslator.BuildQuery(Expression expression)
   at MongoDB.Driver.Linq.SelectQuery.Execute()
   at MongoDB.Driver.Linq.MongoQueryable`1.GetEnumerator()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)"

var result = _users.Where(u =>
                        u.Profile.AttendedSchools.Any(y =>
                            x.Institution.Id == y.Institution.Id // same school
                            // very long expression for all kinds of year intersection
                            && (
                                (!x.ToPresent && !y.ToPresent && x.FromYear <= y.ToYear && y.FromYear <= x.ToYear) // to present is not set
                                || (x.ToPresent && !y.ToPresent && x.FromYear <= y.ToYear) // first guy is in school now
                                || (!x.ToPresent && y.ToPresent && y.FromYear <= x.ToYear) // second guy is in school now
                                || (x.ToPresent && y.ToPresent) // both is in school now
                            )