Fix Trigger Form with Empty Object Default (#46872)

Author: jscheffl

airflow/www/templates/airflow/trigger.html

@@ -120,7 +120,7 @@
     {% elif form_details.schema and "object" in form_details.schema.type %}
       <textarea class="form-control" name="element_{{ form_key }}" id="element_{{ form_key }}" valuetype="object" rows="6"
         {%- if not "null" in form_details.schema.type %} required=""{% endif -%}>
-        {%- if form_details.value %}
+        {%- if form_details.value != None %}
           {{- form_details.value | tojson() -}}
         {% endif -%}
       </textarea>