Add error handling for admin lookups

app/templates/lookup.html

@@ -16,6 +16,18 @@
     </form>
     </div>
 
+    {% if error %}
+    <div class="box error-box">
+        {% if error.value == "NOT_FOUND" %}
+        <p>The remote object was deleted.</p>
+        {% elif error.value == "TIMEOUT" %}
+        <p>Lookup timed out, please try refreshing the page.</p>
+        {% else %}
+        <p>Unexpected error, please check the logs and report an issue if needed.</p>
+        {% endif %}
+    </div>
+    {% endif %}
+
     {% if ap_object and ap_object.ap_type in actor_types %}
     {{ utils.display_actor(ap_object, actors_metadata) }}
     {% elif ap_object %}