title: Fluid array, if all elements are deleted the array is not empty, but a string
body: <p>When I have an array in flux:</p>
  
  <pre><code>&lt;flux:form.section name="links" label="Links"&gt;
      &lt;flux:form.object name="link" label="Link"&gt;
  
          &lt;flux:field.input name="linktext" label="Linktext"/&gt;
  
      &lt;/flux:form.object&gt;
  &lt;/flux:form.section&gt;
  </code></pre>
  
  <p>I first check if the array is set before I render it with fluid:</p>
  
  <pre><code>&lt;f:if condition="{links}"&gt;
  &lt;ul class="menulinks"&gt;
      &lt;f:for each="{links}" as="linkelement"&gt; 
          &lt;li&gt;{linkelement.link.linktext}&lt;/li&gt;
      &lt;/f:for&gt;
  &lt;/ul&gt;
  &lt;/f:if&gt;
  </code></pre>
  
  <p>This works. But if there were items set but then deleted, {links} is not empty. It is set as a string with a whitespace <code>" "</code>. And that means the condition in the if-Tag returns true.</p>
  
  <p>And this can lead to an error. In this case I had an error in the backend, but not on the frontend. Even I used nearly the same code in <code>&lt;f:section name="Preview"&gt;</code> and <code>&lt;f:section name="Main"&gt;</code>.</p>
  
  <p>My idea was to check the type of <code>{links}</code> and only return true if the type is array. But I am not sure if this is possible with fluid. What other options I have?</p>
  
  <p>The errorreport I see in the backend:</p>
  
  <pre><code>The argument "each" was registered with type "array", but is of type "string" in view helper "TYPO3\CMS\Fluid\ViewHelpers\ForViewHelper"
  </code></pre>