Sites child and suppliers in the same table using suppliers rest api

Summary

Trying to fetch the sites data in the same table as a suppliers using suppliers rest-api

Content

Hi when I tried to Apply this blog https://blogs.oracle.com/shay/showing-parentchild-in-a-single-table-in-visual-builder to the case of suppliers and sites  using this rest api  /fscmRestApi/resources/11.13.18.05/suppliers/{SupplierId} 

 

the call of the  rest point  work very well, 

but seems that I have some problem with assigning child site to  the array of data provider.

 

 Thank in advance for your support

Following  The erorrs :

action.js:46 [VB (ERROR), /vb/action/builtin/assignVariablesAction]: Action assignVariables1_6gfzfta25 failed. TypeError: Cannot read property 'SupplierId' of null