Topic on Extension talk:RottenLinks

Yes, MW 1.27.x is supported with adapted "extension.json" file. See below and use at your own risk.

This makes the extension incompatible with MW 1.28 and lower. Are there other things what make the code incompatible with e.g. MW 1.27?

I have tested this extension on MW 1.27.5 and it works without issues. However you have to replace the content of the "extension.json" file with the following:

{
        "name": "RottenLinks",
        "version": "0.0.5",
        "author": "John Lewis",
        "descriptionmsg": "rottenlinks-desc",
        "license-name": "GPL-3.0-or-later",
        "url": "https://github.com/miraheze/RottenLinks",
        "type": "specialpage",
        "SpecialPages": {
                "RottenLinks": "SpecialRottenLinks"
        },
        "MessagesDirs": {
                "RottenLinks": [
                        "i18n"
                ]
        },
        "AutoloadClasses": {
                "RottenLinks": "includes/RottenLinks.php",
                "RottenLinksHooks": "includes/RottenLinksHooks.php",
                "RottenLinksPager": "includes/RottenLinksPager.php",
                "SpecialRottenLinks": "includes/SpecialRottenLinks.php"
        },
        "Hooks": {
                "LoadExtensionSchemaUpdates": [
                        "RottenLinksHooks::fnRottenLinksSchemaUpdates"
                ]
        },
        "config": {
                "RottenLinksBadCodes": [ "0", "400", "401", "403", "404", "405", "502", "503", "504" ],
                "RottenLinksCurlTimeout": 30,
                "RottenLinksExcludeProtocols": [ "tel", "mailto" ]
        },
        "manifest_version": 1
}