2016 – How to call a JavaScript inline of Item display template?

I am editing an Item Display Template (for a content search webpart) on SP2016 enterprise.

In the display template (Item_LargePicture.html), I inserted a JavaScript function to randomly return a image tag (e.g. <img src="https://sharepoint.stackexchange.com/sites/os/PublishingImages/thumbs/01.jpg" alt=""> ). The function named getImageTag().

In the main html part of template I call my JS function like below syntax:

    <span style="display: table-cell;width: 50%">
<article id="_#= containerId =#_" data-displaytemplate="ItemLargePicture"> 

            <a class="image fit thumb" href="_#= linkURL =#_" title="_#= $htmlEncode(line1) =#_" id="_#= pictureLinkId =#_">
                
                <!--#_
                     document.write(getImageTag());
                 _#-->

            </a>
            <span class="text-block" id="_#= dataContainerId =#_">
                <a href="_#= linkURL =#_" title="_#= $htmlEncode(line1) =#_" id="_#= line1LinkId =#_">
                    <h3 id="_#= line1Id =#_"> _#= line1 =#_</h3>
                </a>
            </span>
</article></span>

When I load the sharepoint page with display template, all I got is “Display Error: The display template had an error. You can correct it by fixing the template or by changing the display template used in either the Web Part properties or Result Types.” I cannot debug with above error. Could you advise the correct syntax?