"Undefined index" error when accessing some model admins

[GuySartorelli]

Module version(s) affected

4.13.x

Description

Some model admins get this error when you try to access them:

[Notice] Undefined index: dataClass
GET /admin/registry/
Line 626 in /var/www/html/vendor/silverstripe/admin/code/ModelAdmin.php

The isset() is checking for the wrong thing.

How to reproduce

Install frameworktest, then go to the registry admin. It should blow up immediately.

Possible Solution

No response

Additional Context

No response

Validations

• [X] Check that there isn't already an issue that reports the same bug
• [X] Double check that your reproduction steps work in a fresh installation of silverstripe/installer (with any code examples you've provided)

PRs

• https://github.com/silverstripe/silverstripe-admin/pull/1687

[emteknetnz]

Linked PR has been merged, it will auto-tag shortly