Account for edge case where user deleted leading separator.

        var extraTextAfterNet = m[2];

        var partToSearch = m[1];

        var foundAtPosition = -1;

        var escapedSeparator = reEscape(opts.extra_networks_add_text_separator);

        var escapedSeparator = `(?:${reEscape(opts.extra_networks_add_text_separator)})?`;

        var re = new RegExp(escapedSeparator + re_extranet_str, 'g');

        newTextareaText = textarea.value.replaceAll(re, function(found, net, pos) {

            m = found.match(re_extranet);