Fix empty options messing up selected options

ckanext/odsh/templates/macros/form.html

@@ -179,9 +179,11 @@ is_required=false) %}
       <select id="{{ 'field-' ~ (id or name) ~ '-value' if is_extra else (id or name) }}" name="{{ 'extras__' ~ index ~ '__value' if is_extra else (name) }}" 
               {{ attributes(attrs) }} data-module="autocomplete"{% if is_multiple %} multiple{% endif %}>
           {% for option in options %}
+            {% if option.key %}
               <option value="{{ option.key }}"{% if option.key in selected %} selected="selected"{% endif %}>
                   {{ option.text or option.value }}
               </option>
+            {% endif %}
           {% endfor %}
       </select>
     </div>