I've got a XSLT template that checks for 2 available properties on a collection of nodes. I would like to test whether or not the first property field is empty or null, and if it is use the second property, but the test for empty or null is causing an macro load error on the page. Here is my code:

<xsl:template name="output-cell">
  <xsl:param name="node" />
  <xsl:param name="class" />

  <td class="listing {$class}" categories="{$node/categories}">
    <xsl:choose>
      <xsl:when test="$node/url != '' ">
        <a href="{$node/url}">
          <xsl:value-of select="$node/@nodeName" />
        </a>
      </xsl:when>
      <xsl:otherwise>
          <a href="{umbraco.library:NiceUrl($node/internalPage)}">
          <xsl:value-of select="$node/@nodeName" />
        </a>
      </xsl:otherwise>
    </xsl:choose>
  </td>

</xsl:template>