message: STRUCT not a LIST
diff: @@ -178,9 +178,9 @@ SELECT [NULL] UNION ALL SELECT [True]
  # nulls in structs
  query I
  -SELECT [NULL]
  +SELECT {'x': NULL}
  ----
  -[NULL]
  +{'x': NULL}
  query I
  SELECT {'x': NULL} UNION ALL SELECT {'x': True}
  