Can’t Reference a Preprojection ID in a Postprojection order

You can’t reference a preprojection ID in a postprojection order operation. If you do, the code throws an error. (Projection is another term for a foreach operation.)
Important

Important

This change may break existing SAQL code. Update existing code to use this new behavior.

This code throws an error:
q = load "0Fbxx000000002qCAA/0Fcxx000000002WCAQ";
q = group q by 'FirstName';
q = foreach q generate sum('mea_mm10M') as 'sum_mm10M';
q = order q by 'FirstName' desc;
This code is valid:
q = load "0Fbxx000000002qCAA/0Fcxx000000002WCAQ";
q = group q by 'FirstName';
q = foreach q generate 'FirstName' as 'User_FirstName', sum('mea_mm10M') as 'sum_mm10M';
q = order q by 'User_FirstName' desc;