AbortController problem for update queries when bundled

Hi Ruben,

thank you for this library. It works well but I encountered a small problem with the AbortController when sending update queries. It's working when executed with Node, but the 'fetchUpdate' function has an error when it's bundled (with browserify or React).

JavaScript project
fetch-sparql-endpoint v2.3.2
abort-controller v3.0.0

Here is the problem in the browser:

const abort_controller_1 = require("abort-controller");

async fetchUpdate(endpoint, query) {
    const abortController = new abort_controller_1.AbortController(); // TypeError: abort_controller_1.AbortController is not a constructor
    const init = {
        method: 'POST',
        headers: {
            'content-type': 'application/sparql-update',
        },
        body: query,
        signal: abortController.signal,
    };
    await this.handleFetchCall(endpoint, init, { ignoreBody: true });
    abortController.abort();
}

A quick workaround was:

    let abortController;
    if (typeof window === 'undefined') { // --> nodeJS
        abortController = new abort_controller_1.AbortController();
    } else { // --> browser
        abortController = new AbortController();
    }

rubensworks / fetch-sparql-endpoint.js

AbortController problem for update queries when bundled #43