Optional attribute with xls:if

[Nearata]

hello!

my goal is to use this attribute internally to update the content the end-user will see.

# Configure.php

'[nearata-dsts login="{SIMPLETEXT1}" like="{SIMPLETEXT2}" reply="{SIMPLETEXT3}" error="{SIMPLETEXT4;optional}"]{ANYTHING}[/nearata-dsts]',
resolve(Factory::class)->make('nearata-dsts::bbcode')

# bbcode.blade.php

<div class="NearataDstsBBCode">
    <div class="title">{{ $translator->trans('nearata-dsts.forum.post.bbcode.hidden_content') }}</div>
    <div class="content">
        {ANYTHING}
    </div>
    {SIMPLETEXT4} // if i use @error it doesnt work
</div>

i tried

# bbcode.blade.php

...

// no working code
<xsl:if test="@error = ''">
    {ANYTHING}
</xsl:if>
<xsl:if test="@error != ''">
    {SIMPLETEXT4} // {@error} doesnt work
</xsl:if>

but it sounds like error doesnt exist in view

Illuminate \ View \ ViewException (E_ERROR)
syntax error, unexpected end of file, expecting "elseif" or "else" or "endif" (View: D:\GitHub Repositories\Nearata\flarum-ext-dsts\views\bbcode.blade.php)

[Nearata]

my bad, error is a variable in the view