PHP warnings in SettingsService.php when saving Notes settings (_route treated as setting) #2054

When Notes settings are saved, Notes 6.1.0 generates PHP warnings in
lib/Service/SettingsService.php line 165.

The request contains _route, which appears to be handled as if it were a
Notes setting. SettingsService.php accesses $this->attrs[$name]['default']
on line 165 before checking array_key_exists($name, $this->attrs) on the
following line.

Each affected PUT request to /index.php/apps/notes/settings generated
multiple PHP warnings.

Steps to reproduce

1. Open the Notes app.
2. Change/save a Notes setting.
3. Check nextcloud.log.

Expected behaviour

Notes settings should be saved without PHP warnings. Request parameters such
as _route should not be treated as Notes settings.

Actual behaviour

Saving Notes settings generates warnings such as:

Undefined array key "_route" at
/apps/notes/lib/Service/SettingsService.php#165

Trying to access array offset on null at
/apps/notes/lib/Service/SettingsService.php#165

The warnings were associated with:

PUT /index.php/apps/notes/settings

Screenshots

Not applicable.

Server

• Notes app version: 6.1.0
• Nextcloud version: 35.0.1
• OS: CloudLinux (shared hosting)
• Web server: LiteSpeed
• PHP version: 8.4.25
• Database: MariaDB 11.4.13

Nextcloud configuration:

No custom changes have been made to the Notes app.

Client

• Browser (incl. version): Chromium-based browser
• OS: Windows

Log files

Relevant nextcloud.log warnings:

Undefined array key "_route" at
/home/malamute/public_html/files/apps/notes/lib/Service/SettingsService.php#165

Trying to access array offset on null at
/home/malamute/public_html/files/apps/notes/lib/Service/SettingsService.php#165

Both observed request IDs used:

method: PUT
url: /index.php/apps/notes/settings