<script src="{$src}?merchant={$config->merchantId}" {if $config->sandbox}data-env="sandbox"{/if} data-currency="{$config->currency}"  {!$pluginSettings}></script>


Fix JS path in template
<script src="{$basePath}/js/{$src}?merchant={$config->merchantId}" {if $config->sandbox}data-env="sandbox"{/if} data-currency="{$config->currency}"  {!$pluginSettings}></script>