Customize error pages

[f-necas]

I'm not sure about the /config route. I did this way in order to let other applications to be able to retrieve config from the gateway.

Everything is customizable with the georchestraStylesheet set in default.properties from datadir.

Previews :

In blue :

[landryb]

I like the '500' -> maintenance shortcut, to avoid saying 'something is badly broken' ;)

[pmauduit]

I like the '500' -> maintenance shortcut, to avoid saying 'something is badly broken' ;)

I'd have put a picture of you with your sysadmin teeshirt "like riding a bike, except that everything is in fire and you are in hell" ;-)

[fvanderbiest]

Not sure I fully understand what's at stake here.
Would you be able to develop in the PR description what it does and why ?
Ideally, people should not have to read the code to understand what the PR does ;-)

I think I do not really understand the need for an XHR call to /config.

[f-necas]

It calls the stylesheet (if) set in the datadir in order to customize the error page if wanted. (like colors font etc...).

If no stylesheet is set, it just displays this new page with georchestra's colors.

[fvanderbiest]

OK, got it, thanks !

[fvanderbiest]

Requesting @groldan 's review too

[groldan]

Almost fell off the bed when I just woke up and saw this notification saying you added a /config route to the gateway. Thought it was exposing the config service.
Please be more specific 😀, like in "Add a custom entry point to retrieve the error pages stylesheet..." or so. Same for the commits, it doesn't say much and commits arre independent of GitHub.
Other than that great work.

[github-actions]

💚 All backports created successfully

Status	Branch	Result
✅	1.1.x

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