Cosmos: bad exception for queries with aggregate selecting non-mapped type

[maumar]

query:

ctx.Orders.Average(o => o.ShipVia)

exception:

System.Collections.Generic.KeyNotFoundException : The given key 'EmptyProjectionMember' was not present in the dictionary.
  Stack Trace: 
    Dictionary`2.get_Item(TKey key)
    SelectExpression.GetMappedProjection(ProjectionMember projectionMember) line 131
    CosmosQueryableMethodTranslatingExpressionVisitor.TranslateAverage(ShapedQueryExpression source, LambdaExpression selector, Type resultType) line 193
    QueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression) line 119
    MethodCallExpression.Accept(ExpressionVisitor visitor)
    ExpressionVisitor.Visit(Expression node)
    QueryCompilationContext.CreateQueryExecutor[TResult](Expression query) line 91
    Database.CompileQuery[TResult](Expression query, Boolean async) line 71
    QueryCompiler.CompileQueryCore[TResult](IDatabase database, Expression query, IModel model, Boolean async) line 112
    <>c__DisplayClass9_0`1.<Execute>b__0() line 96
    CompiledQueryCache.GetOrAddQueryCore[TFunc](Object cacheKey, Func`1 compiler) line 76
    CompiledQueryCache.GetOrAddQuery[TResult](Object cacheKey, Func`1 compiler) line 51
    QueryCompiler.Execute[TResult](Expression query) line 92
    EntityQueryProvider.Execute[TResult](Expression expression) line 79
    Queryable.Average[TSource](IQueryable`1 source, Expression`1 selector)
    QueryAsserter`1.AssertAverage[TResult](Func`2 actualQuery, Func`2 expectedQuery, Expression`1 actualSelector, Expression`1 expectedSelector, Action`2 asserter, Boolean async) line 1305
    NorthwindAggregateOperatorsQueryTestBase`1.Average_with_unmapped_property_access_throws_meaningful_exception(Boolean async) line 1896