Internal error when creating analyst table, analyst table contains nil column

[edongashi]

When I try to create the following analyst table:

SELECT * FROM (SELECT uid, SUM(price) FROM purchases GROUP BY 1) t

It fails with:

** (UndefinedFunctionError) function nil.access/0 is undefined
    nil.access()
    (cloak) lib/cloak/sql/query/lenses.ex:441: Cloak.Sql.Query.Lenses.unselectable_column?/1
    (lens) lib/lens.ex:488: anonymous fn/3 in Lens.filter/2
    (lens) lib/lens.ex:50: anonymous fn/2 in Lens.root/0
    (lens) lib/lens.ex:487: anonymous fn/4 in Lens.filter/2
    (lens) lib/lens.ex:484: anonymous fn/4 in Lens.filter/2
    (cloak) lib/cloak/sql/compiler/helpers.ex:193: Cloak.Sql.Compiler.Helpers.unselectable_selected_expression?/1
    (cloak) lib/cloak/sql/compiler/helpers.ex:144: anonymous fn/1 in Cloak.Sql.Compiler.Helpers.create_table_from_columns/3

It appears that a nil column is leaking into the analyst table's columns...