fix: api usage

public/src/client/account/header.js

@@ -116,11 +116,14 @@ define('forum/account/header', [
 	}
 
 	function toggleFollow(type) {
-		api[type === 'follow' ? 'put' : 'delete']('/users/' + ajaxify.data.uid + '/follow', undefined, () => {
+		api[type === 'follow' ? 'put' : 'delete']('/users/' + ajaxify.data.uid + '/follow', undefined, function (err) {
+			if (err) {
+				return app.alertError(err);
+			}
 			components.get('account/follow').toggleClass('hide', type === 'follow');
 			components.get('account/unfollow').toggleClass('hide', type === 'unfollow');
 			app.alertSuccess('[[global:alert.' + type + ', ' + ajaxify.data.username + ']]');
-		}, 'default');
+		});
 
 		return false;
 	}