settings-sync: handle missing /ubus endpoint instead of parsing 404 HTML as JSON

[ang3el7z]

Environment

• Proton2025 v1.3.0
• OpenWrt router with luci-theme-proton2025, luci-base, rpcd, rpcd-mod-luci, and uhttpd installed

Problem

After opening LuCI, the browser console reports:

[Proton2025] Failed to sync from UCI: SyntaxError: Unexpected token "<", "<h1>Not Fo"... is not valid JSON

The error originates from settings-sync.js in syncFromUci(). The script calls response.json() without checking the HTTP response.

Investigation

The RPC object itself is available and works locally:

ubus list luci.proton-settings
ubus call luci.proton-settings getSettings

Both commands succeed; getSettings returns the expected settings object.

However, the HTTP endpoints used by settings-sync.js are unavailable on this router:

curl -i -H "Content-Type: application/json" --data "{}" http://ROUTER/ubus
curl -i -H "Content-Type: application/json" --data "{}" http://ROUTER/ubus/

Both return:

HTTP/1.1 404 Not Found
Content-Type: text/html

<h1>Not Found</h1>

The installed uhttpd configuration has no ubus_prefix or ubus socket configuration, and no HTTP ubus gateway module is installed.

Expected behavior

1. Theme installation should either ensure the HTTP ubus gateway required by settings-sync.js is available/configured, or use the supported LuCI RPC path for the target OpenWrt release.
2. settings-sync.js should check response.ok and the response content type before calling response.json(), then log a clear actionable error instead of a JSON SyntaxError.

This does not affect the theme RPC backend itself; it only breaks browser-to-UCI synchronization.

[ang3el7z]

Confirmed local fix on the affected router:

apk add uhttpd-mod-ubus
uci set uhttpd.main.ubus_prefix='/ubus'\nuci set uhttpd.main.ubus_socket='/var/run/ubus/ubus.sock'\nuci commit uhttpd\n/etc/init.d/uhttpd restart\n```\n\nAfter this change, a POST to `/ubus/` returns `HTTP 200` with `Content-Type: application/json` instead of the previous HTML `404 Not Found`. The unauthenticated probe correctly returns a JSON `Access denied` error; authenticated LuCI requests can then reach `luci.proton-settings` through the theme ACL.\n\nThis suggests that `uhttpd-mod-ubus` should be a runtime dependency of the theme when `settings-sync.js` relies on `/ubus/`, with the standard `ubus_prefix` and `ubus_socket` configuration documented or ensured during installation. It would still be useful for the client code to report a clear HTTP error when the endpoint is missing.

[ChesterGoodiny]

Спасибо за расследование и решение, поправим👍