Add compatibility with MediaWiki 1.42 and later

[JeroenDeDauw]

From @etlel:

I updated to 1.0.4 into wikibase-release-pipeline (Docker). Autocomplete is broken and I get two JS errors:

Uncaught TypeError: this is undefined
jquery.ui.mediasuggester.js:96:26

or

Uncaught TypeError: response.query is undefined
jquery.ui.mediasuggester.js:71:52

The same backend error remains on saving.

Tested on MW 1.42.3 and 1.44.0-alpha.

[etlel]

In some configurations when there are no results, https://github.com/wikimedia/mediawiki/blob/master/includes/api/ApiQuerySearch.php is returning this:

{
    "error": {
        "code": "search-text-disabled",
        "info": "\"text\" search is disabled.",
        "*": "See .../w/api.php for API usage. Subscribe to the mediawiki-api-announce mailing list at <https://lists.wikimedia.org/postorius/lists/mediawiki-api-announce.lists.wikimedia.org/> for notice of API deprecations and breaking changes."
    }
}

Just verify that response.query exists can prevent a js error. This is not breaking the normal use. I fixed some unrelated code and the extension is now working fairly on MW 1.44.

[hrideshmg]

I get the same error but only when there exists two or more file's which have the same term in their names. Might look into it later, version is 1.42.3 btw

[JeroenDeDauw]

Done in 2.0.0 release