I don't think we should replace the array with an error message.

The current solution allows power users:

• to check the groups a contributor belongs to and so be able to answer some questions like "why can't I rename a page? I were added to confirmed group." "No, you weren't.".
• to learn each time they see this page the available permissions groups.

(In reply to comment #1)

I don't think we should replace the array with an error message.

The current solution allows power users:

• to check the groups a contributor belongs to and so be able to answer some

questions like "why can't I rename a page? I were added to confirmed group."
"No, you weren't.".

For non-existent groups? Thats what I speak about.

• to learn each time they see this page the available permissions groups.

Good point. But a message on top which says "This group does not exist" would help.

I checked several special pages and were a little confused: I thought this were a user/global group setting.

[ Taking this bug. Rriority: low ]

Dereckson: This issue has been assigned to you 12 months ago.
Do you still plan to work on this issue?
Only in case you do not plan to work on this issue anymore, should the assignee be set back to default and the bug status changed from ASSIGNED to NEW/UNCONFIRMED? Thanks.

Dereckson: I am resetting the assignee of this issue to default because there has been no progress in the last months. Feel free to take it again when you are actually planning to fix this. Thanks.

Change 139653 had a related patch set uploaded by Gerrit Patch Uploader:
Error on GlobalGroupPermssions for group without rights

https://gerrit.wikimedia.org/r/139653

Change 139653 merged by jenkins-bot:
Show error on GlobalGroupPerms. for group without rights

https://gerrit.wikimedia.org/r/139653