Refactor group and music game models to use UniqueConstraint; update form error handling in templates

base/static/css/main.css

@@ -64,3 +64,9 @@ article.message {
         color: var(--pico-color-red-500);
     }
 }
+
+.form-error::before  {
+    margin-right: .5em;
+    font-family: remixicon;
+    content: "\eca0";
+}

base/templates/base/form.html

@@ -1,8 +1,4 @@
-{% if form.non_field_errors %}
-    <ul class="form-errors">
-        {% for error in form.non_field_errors %}<li>{{ error }}</li>{% endfor %}
-    </ul>
-{% endif %}
+{% for error in form.non_field_errors %}<article class="message error">{{ error }}</article>{% endfor %}
 <form method="post" {% if action %}action="{% url action %}"{% endif %}>
     {% csrf_token %}
     <fieldset>
@@ -10,12 +6,10 @@
             <label>
                 {{ field.label }}
                 {{ field }}
+                {% if field.errors %}
+                    <small id="{{ field.errors.field_id }}_error" class="form-error">{{ field.errors|join:", " }}</small>
+                {% endif %}
             </label>
-            {% if field.errors %}
-                <ul class="form-errors">
-                    {% for error in field.errors %}<li>{{ error }}</li>{% endfor %}
-                </ul>
-            {% endif %}
         {% endfor %}
     </fieldset>
     <input type="submit" {% if submit %}value="{{ submit }}"{% endif %}>