fixed no image message on assignments

assignments/templates/assignments/DetailView.html

@@ -18,7 +18,7 @@ Name: {{assignment.name}}<br>
 Description: {% if assignment.description != None and assignment.description != '' %}{{ assignment.description }}{% else %}No description provided.{% endif %}<br>
 Perfect score: {{assignment.max_points}}<br>
 Passing score: {{assignment.passing_score}}<br>
-Image: {% if assignment.image != None %}<br><img src="{% get_media_prefix %}{{assignment.image}}" id="assignment-image" alt="Image failed to load.">{% else %}No image provided.{% endif %}<br>
+Image: {% if assignment.image != None and assignment.image != '' %}<br><img src="{% get_media_prefix %}{{assignment.image}}" id="assignment-image" alt="Image failed to load.">{% else %}No image provided.{% endif %}<br>
 </span>
 
 {% endblock %}
\ No newline at end of file