hardcoded backends

[WolfgangFahl]

grep wikidata scholia/app/static/scholia.js 

results in

        "https://query.wikidata.org/bigdata/namespace/wdq/sparql",
        "https://query.wikidata.org/sparql",
        "https://query.wikidata.org/#",
    if (!url) url = "https://query.wikidata.org/sparql";
    if (!editURL) editURL = "https://query.wikidata.org/#";
        "https://query.wikidata.org/sparql",
        "https://query.wikidata.org/",
    if (!url) url = "https://query.wikidata.org/sparql";
    if (!editURL) editURL = "https://query.wikidata.org/#";
        "https://query.wikidata.org/sparql",
        "https://query.wikidata.org/#",
        "https://query.wikidata.org/embed.html#",
    if (!url) url = "https://query.wikidata.org/sparql";
    if (!editURL) editURL = "https://query.wikidata.org/#";
    if (!embedURL) embedURL = "https://query.wikidata.org/embed.html#";
    const wikidata_sparql = url + "?query=" + encodeURIComponent(sparql);
    const wikidata_query = editURL + encodeURIComponent(sparql);
        url: wikidata_sparql,
                    '<a href="' + wikidata_query + '" target="_blank">modifying it</a>.</p>');
        "https://query.wikidata.org/sparql",
        const sparqlURL = 'https://query.wikidata.org/bigdata/namespace/wdq/sparql?query=' + 
            var organismScholia = dataValues.organism.replace("http://www.wikidata.org/entity/","https://scholia.toolforge.org/taxon/");
        "https://query.wikidata.org/sparql",
     if (!endpointUrl) endpointUrl = "https://query.wikidata.org/sparql";

which seems to not properly handling the endpoint as a configurable entity.

https://scholia.wikidata.dbis.rwth-aachen.de/event-series/

for instances shows a

  This query has timed out, we recommend that you follow the link to the Wikidata Query Service below to modify the query to be less intensive. 

which is IMHO misleading since the code answers this on any failure instead of showing the real reason of the problem.

[WolfgangFahl]

https://scholia.wikidata.dbis.rwth-aachen.de/backend shows the backend on the RWTH machine which should have the option of non default timeouts and react quite quickly given the small load it should have at this time.

[WolfgangFahl]

I might try

// Accepts arguments to see the real error
.fail(function (jqXHR, textStatus, errorThrown) { 
    $('#' + loaderID).remove();
    
    // Create a dynamic message
    var msg = "Error: " + textStatus + " - " + errorThrown;
    
    $(element).prepend(
        '<p>Query failed on backend.</p><p>Details: <code>' + msg + '</code></p>'
    );
});