Backup timeout improvement

[FastFrank]

The Problem

Add this before xhr.ontimeout = (e) => { // XMLHttpRequest timed out in backup.html around line 148:

xhr.onprogress = (e) => { // XMLHttpRequest progress ... extend timeout
    xhr.timeout = xhr.timeout + 500;
};
xhr.onerror = (e) => { // XMLHttpRequest error loading
    console.log("Error on fetching " + url + "!");
    if (retry > 5) {
        setStatus("<span style=\"color: red\">Backup failed, please restart the device and try again!</span>");
    }
    else {
        fetchFiles(urls, filesData, index, retry+1, zipFilename);
    }
};

Version

15.0.3

Logfile

Timeout occurs although progress is made with downloading...

Expected Behavior

No response

Screenshots

No response

Additional Context

No response

[caco3]

Thanks, I added it in #2170