feat: error handling in unsubscribe.tpl

templates/unsubscribe.tpl

@@ -1,6 +1,14 @@
+{{{ if !error }}}
 <div class="alert alert-success">
 	<strong>[[global:alert.success]]</strong>
 	<p>[[email:unsub.success, {payload.template}]]</p>
+{{{ else }}}
+<div class="alert alert-warning">
+	<strong>[[email:unsub.failure.title]]</strong>
+	<p>[[email:unsub.failure.message, {error}, {config.relative_path}/me/settings]]</p>
+{{{ end }}}
+	<hr />
+
 	<p>
 		<a href="{config.relative_path}/">[[notifications:back_to_home, {config.siteTitle}]]</a>
 	</p>