How can I query Stardog using Yasgui

Question

I want to use Yasgui to run queries against a Stardog knowledge graph. The request requires specific headers.

Since I only want one tab to query Stardog, I pass a unique configuration object when adding that tab to my front-end. The query returns the expected results in Chrome but when using Firefox I get an error. In Firefox developer tools the request I sent using the front-end is listed as 'blocked'. After clicking 'edit and resend' it now works as expected.

//setting required headers in configuration object
requestConfig: {
    endpoint: /*[[${triplestoreEndpoint}]]*/ "SparqlEndpointToBeReplacedByThyMeLeaf",
    headers: () => ({
        Accept:'application/sparql-results+json',
        Authorization: 'Basic YWRtaW46YWRtaW4=' // Stardog specific headers with default authentication
    }),
    method: 'GET'
},

//passing configuration object when adding my custom tab
yasgui.addTab(
    false,
    {...Yasgui.Tab.getDefaults(), name:name, id:id, requestConfig:requestConfig}
);

I already tried deactivating the CORS policy in my Firefox browser.

Can someone tell me how to configure Yasgui to work with Stardog?

Thanks in advance