Uncaught TypeError: Cannot convert object to primitive value

I’m seeing the following error upgrading from 2.9 to 2.11.0:

Uncaught TypeError: Cannot convert object to primitive value

toString is being called on an array containing objects of label/value pairs:

toString appears to be initiated from an assert statement in the set function:

I believe set is being initiated on a component property in a template from a helper. In this case, the group helper simply returns the params that were passed into it:

checkboxes=(group
  (hash label="Foo" value="foo")
  (hash label="Bar" value="bar")
)

I created an Ember Twiddle but I was unable to reproduce the error: https://ember-twiddle.com/ae1d147bd798f9ba0c499c271c743eb3?openFiles=templates.application.hbs%2Ctemplates.components.my-component.hbs

[rwjblue]

The rough issue is this:

The assertion is attempting to convert content to a string (to make the error message nice), but calling Object.create(null) + '' throws an error…

[mrgenesis]

The rough issue is this:

The assertion is attempting to convert content to a string (to make the error message nice), but calling Object.create(null) + '' throws an error…

It really solved my trouble. I did put an object in string ${val}, this was having error.