[RSS Feed/News] If there is no image, use the default image?

[XenForo]

Hello, I'm looking for a solution on this
If there is no image, use the default image

PHP:

<xf:if is="?">
                      <img src="{$xf.options.boardUrl}/styles/uls/kat/{$node.node_id}.jpg">
                       <xf:else />
                     <img src="{$xf.options.boardUrl}/styles/uls/kat/default.jpg">
                  </xf:if>

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