Brooklyn issue (10.0.4): Visualforce Remoting Exception: Ending position out of bounds: -1 [object O

We are testing Brooklyn upgrade and this is one of the errors we are getting on an existing row action
Visualforce Remoting Exception: Ending position out of bounds: -1

Row action: this is mix of blockUI, setCondition, createRow, updateRow , custom, save action with on error actions and unblockUI.

When removing the last save model action, I can get to the unblockUI. The save action saves a new model with an external id. I narrowed down the issue to a specific updateRow action which tries to update a field from another field via the merge field syntax.

Prior to the upgrade, this is not an issue. I see the same error in the web console but I’m able to complete the action and get the on error message from the save action.

  1. When I use a snippet to do the model save, it appears that the callback is not being invoked. ‘saving contact’ is logged but failed did not get logged.

    var newModel = skuid.$M(‘newModel’);
     console.log(‘saving contact’);    
         {callback: function(result){
        if (result.totalsuccess) {
        } else {

    2) When I use Apex to do the insert of the record above, I got a validation error, which is the correct behavior. Skuid Rockaway can see the error and return the on error message and move onto the unblock ui action. In Brookly, it’s stuck on the skuid remoting stub error.