PAjax request for CMS page throws "Cannot mutate DI container"

[maxime-rainville]

Affected version

• colymba/gridfield-bulk-editing-tools 3.0.0-beta4
• Silverstripe 4.3

Description

If you are viewing a page in the CMS and then navigate to a page containing a gridfield, you will get a nasty JS errors.

Error: "Cannot mutate DI container after it has been initialised"

The error stack doesn't explicitly point to anything in colymba/gridfield-bulk-editing-tools. However, the error goes away if your remove the module.

If you refresh that page you do not get any error, even on navigation.

This got notice while working on silverstripe/silverstripe-cms#2230. It use to block other request, but it got fix by silverstripe/silverstripe-admin#769.

Steps to reproduce

• Start on the admin/pages url.
• Navigate to a page with a Gridfield.

Notice the error in the console.

https://youtu.be/qJMFiwKbEOU

[robbieaverill]

Also related: #176

I think we need to set aside some time to fix these bugs soon! cc @brynwhyman