If the photo is not uploaded, then how to choose a logo?

Question

Twig

There is pl.picture in which you can upload an image and you need that if the image is not uploaded, then instead of an empty space there should be a specific picture (/img/default.png)

This code does not work (if I put {% if pl.picture |length > 0 %} , then the second default one is simply added to the loaded image):

<img src="{{ env.getConfig("context_root") }}{{ pl.picture }}"
 style="width: 64px; height: 64px; vertical-align: baseline; float: left;"/>
                    
{% if pl.picture |length < 0 %}

  <img src="{{ env.getConfig("context_root") }}/img/default.png" 
 style="width: 64px; height: 64px; vertical-align: baseline; float: left;>

  {% endif %}