[Bug]: PDF viewer fails to load first time around in Safari

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

I get a blank window on Safari 18.6 – except for controls along the top – when clicking on a PDF in the Files app whenever its the first time in a new window. If I then close that viewer and click on the PDF again, it will load fine.

The console log is showing the error:

[Error] TypeError: Right side of assignment cannot be destructured
	Module Code (pdfjs.js:59)

which points to this initialization code:

const {
  AbortException,
  AnnotationEditorLayer,
  AnnotationEditorParamsType,
  AnnotationEditorType,
  AnnotationEditorUIManager,
  AnnotationLayer,
  AnnotationMode,
  build,
  CMapCompressionType,
  createValidAbsoluteUrl,
  DOMSVGFactory,
  FeatureTest,
  getDocument,
  getFilenameFromUrl,
  getPdfFilenameFromUrl,
  getXfaPageViewport,
  GlobalWorkerOptions,
  ImageKind,
  InvalidPDFException,
  isDataScheme,
  isPdfFile,
  MissingPDFException,
  noContextMenu,
  normalizeUnicode,
  OPS,
  PasswordResponses,
  PDFDataRangeTransport,
  PDFDateString,
  PDFWorker,
  PermissionFlag,
  PixelsPerInch,
  PromiseCapability,
  RenderingCancelledException,
  renderTextLayer,
  setLayerDimensions,
  shadow,
  UnexpectedResponseException,
  updateTextLayer,
  Util,
  VerbosityLevel,
  version,
  XfaLayer,
} = globalThis.pdfjsLib;

so I'm guessing that this is some async issue to do with loading.

Steps to reproduce

1. Open a "Private" window (easiest way to get a fresh session)
2. Go into Files app
3. Click on any PDF

Expected behavior

The PDF loads properly first time.

Nextcloud Server version

31

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.3

Web server

Nginx

Database engine version

MySQL

Is this bug present after an update or on a fresh install?

None

Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

{
    "system": {
        "htaccess.RewriteBase": "\/",
        "memcache.local": "\\OC\\Memcache\\APCu",
        "apps_paths": [
            {
                "path": "\/var\/www\/html\/apps",
                "url": "\/apps",
                "writable": false
            },
            {
                "path": "\/var\/www\/html\/custom_apps",
                "url": "\/custom_apps",
                "writable": true
            }
        ],
        "upgrade.disable-web": true,
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "nextcloud.**NOPE**.com"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "31.0.7.1",
        "overwrite.cli.url": "http:\/\/nextcloud.**NOPE**.com",
        "installed": true,
        "overwritehost": "nextcloud.**NOPE**.com",
        "overwriteprotocol": "https",
        "maintenance": false,
        "maintenance_window_start": 1,
        "loglevel": 2,
        "opcache.memory_consumption": 256,
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpmode": "smtp",
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "25",
        "mail_sendmailmode": "smtp",
        "mysql.utf8mb4": true,
        "allow_user_to_change_display_name": false,
        "lost_password_link": "disabled",
        "oidc_login_client_id": "nextcloud",
        "oidc_login_client_secret": "8vV1oiyR6On3G0HmubFBGzpZ5Y3aGZgV",
        "oidc_login_provider_url": "https:\/\/sso.**NOPE**.com\/realms\/**NOPE**\/",
        "oidc_login_auto_redirect": true,
        "oidc_login_end_session_redirect": true,
        "oidc_login_logout_url": "https:\/\/nextcloud.**NOPE**.com\/apps\/oidc_login\/oidc",
        "oidc_login_use_id_token": false,
        "oidc_login_attributes": {
            "id": "preferred_username",
            "mail": "email",
            "name": "name",
            "groups": "realm_access_roles",
            "is_admin": "realm_access_roles_admin"
        },
        "oidc_login_default_group": "everyone",
        "oidc_login_use_external_storage": false,
        "oidc_login_scope": "profile email",
        "oidc_login_proxy_ldap": false,
        "oidc_login_disable_registration": false,
        "oidc_login_redir_fallback": false,
        "oidc_login_tls_verify": true,
        "oidc_create_groups": false,
        "oidc_login_webdav_enabled": false,
        "oidc_login_password_authentication": false,
        "oidc_login_public_key_caching_time": 86400,
        "oidc_login_min_time_between_jwks_requests": 10,
        "oidc_login_well_known_caching_time": 86400,
        "oidc_login_update_avatar": false,
        "oidc_login_code_challenge_method": "S256",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "default_phone_region": "GB",
        "memcache.distributed": "\\OC\\Memcache\\Redis",
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "password": "***REMOVED SENSITIVE VALUE***",
            "port": 6379
        },
        "app_install_overwrite": []
    }
}

List of activated Apps

Enabled:
  - activity: 4.0.0
  - bruteforcesettings: 4.0.0
  - calendar: 5.3.8
  - circles: 31.0.0
  - cloud_federation_api: 1.14.0
  - comments: 1.21.0
  - contactsinteraction: 1.12.0
  - dashboard: 7.11.0
  - dav: 1.33.0
  - deck: 1.15.2
  - federatedfilesharing: 1.21.0
  - files: 2.3.1
  - files_downloadlimit: 4.0.0
  - files_pdfviewer: 4.0.0
  - files_reminders: 1.4.0
  - files_sharing: 1.23.1
  - files_trashbin: 1.21.0
  - files_versions: 1.24.0
  - firstrunwizard: 4.0.0
  - groupfolders: 19.1.3
  - logreader: 4.0.0
  - lookup_server_connector: 1.19.0
  - nextcloud_announcements: 3.0.0
  - notifications: 4.0.0
  - oauth2: 1.19.1
  - oidc_login: 3.2.2
  - password_policy: 3.0.0
  - polls: 8.1.4
  - privacy: 3.0.0
  - profile: 1.0.0
  - provisioning_api: 1.21.0
  - recommendations: 4.0.0
  - related_resources: 2.0.0
  - richdocuments: 8.7.3
  - serverinfo: 3.0.0
  - settings: 1.14.0
  - sharebymail: 1.21.0
  - spreed: 21.1.2
  - support: 3.0.0
  - survey_client: 3.0.0
  - systemtags: 1.21.1
  - text: 5.0.0
  - theming: 2.6.1
  - theming_customcss: 1.18.0
  - twofactor_backupcodes: 1.20.0
  - twofactor_totp: 13.0.0-dev.0
  - updatenotification: 1.21.0
  - user_status: 1.11.0
  - viewer: 4.0.0
  - weather_status: 1.11.0
  - webhook_listeners: 1.2.0
  - workflowengine: 2.13.0
Disabled:
  - admin_audit: 1.21.0
  - app_api: 5.0.2 (installed 5.0.2)
  - encryption: 2.19.0
  - federation: 1.21.0 (installed 1.21.0)
  - files_3dmodelviewer: 0.0.15 (installed 0.0.15)
  - files_external: 1.23.0
  - htmlviewer: 31.0.0 (installed 31.0.0)
  - photos: 4.0.0 (installed 4.0.0)
  - suspicious_login: 9.0.1
  - twofactor_nextcloud_notification: 5.0.0
  - user_ldap: 1.22.0

Nextcloud Signing status

No errors have been found.

Nextcloud Logs

Additional info

No response

Start by reproducing the failure in a Safari 18.6 private window with the files_pdfviewer app, then inspect the initialization at pdfjs.js:59 and the surrounding PDF.js loading sequence. Done means a PDF loads on its first opening in a new window without the destructuring error, while subsequent openings continue to work.