Impossible to invoke a method ("resize") on a null variable.
{% if page.content_image.isNotEmpty %}
<div class="blog-entry-content-with-image">
{% set picture = page.image(page.content_image.picture.yaml[0]) %}
<figure class="blog-entry-content-with-image__image">
<img srcset="{{ picture.resize(928).url }} 928w, {{ picture.resize(464).url }} 464w"
sizes="464px"
src="{{ picture.resize(928).url }}" alt=""
>
</figure>
<div class="blog-entry-content-with-image__content">
<a href="/blog">