Error adding new poll option (TypeError: Return value of OCA\Polls\Db\Option::getDisplayName() must be of the type string, null returned)

What is going wrong? What did you observe?

When I add a date to a (test) poll I receive the following error:

Steps to reproduce the behavior

New Nextcloud instance
Add polls App
Create new poll with dates
Add a few date options

If applicable, add screenshots to help explain your problem.

How should it work?

Date option should be added without error

Information about your polls installation

Polls version: 3.4.0

Fresh installation or update from a prior version (from which one)?

[ ] First time install
[ ] Update from a prior version Version number of the previous version:
[x] Unsure: The nextcloud instance is quite old (started at version 16). I had some "polls_*" tables in the database and i dropped the tables (and migrations where app='polls' // preferences where appid='polls' ) before installing the app. Maybe I missed some data there.

How did you install this version?(Appstore or describe installation)

[x] Installed from the appstore
[ ] Installed via occ
[ ] Installed via extracting downloaded package to the apps folder

Information about your Instance of Nextcloud

Nextcloud version: 21.0.7

List of activated apps

``` Enabled: - activity: 2.14.3 - apporder: 0.13.0 - bookmarks: 10.0.3 - calendar: 3.0.1 - cloud_federation_api: 1.4.0 - comments: 1.11.0 - contacts: 4.0.6 - contactsinteraction: 1.2.0 - dashboard: 7.1.0 - dav: 1.17.1 - federatedfilesharing: 1.11.0 - federation: 1.11.0 - files: 1.16.0 - files_markdown: 2.3.5 - files_pdfviewer: 2.1.1 - files_rightclick: 1.0.0 - files_sharing: 1.13.1 - files_trashbin: 1.11.0 - files_versions: 1.14.0 - files_videoplayer: 1.10.0 - logreader: 2.6.0 - lookup_server_connector: 1.9.0 - notes: 4.2.0 - notifications: 2.9.0 - oauth2: 1.9.0 - password_policy: 1.11.0 - passwords: 2021.11.20 - phonetrack: 0.6.9 - photos: 1.3.0 - polls: 3.4.0 - previewgenerator: 3.4.0 - privacy: 1.5.0 - provisioning_api: 1.11.0 - recommendations: 1.0.0 - richdocuments: 4.2.3 - settings: 1.3.0 - sharebymail: 1.11.0 - systemtags: 1.11.0 - tasks: 0.14.2 - text: 3.2.0 - theming: 1.12.0 - theming_customcss: 1.10.0 - twofactor_backupcodes: 1.10.0 - twofactor_totp: 6.2.0 - twofactor_u2f: 6.3.0 - twofactor_webauthn: 0.2.14 - viewer: 1.5.0 - weather_status: 1.1.0 - workflowengine: 2.3.1 Disabled: - accessibility - admin_audit - encryption - files_external - firstrunwizard - nextcloud_announcements - serverinfo - support - survey_client - updatenotification - user_ldap - user_status ```

Nextcloud Configuration

``` { "system": { "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 } ], "passwordsalt": "***REMOVED SENSITIVE VALUE***", "secret": "***REMOVED SENSITIVE VALUE***", "trusted_domains": [ "localhost", "***DOMAIN***" ], "trusted_proxies": "***REMOVED SENSITIVE VALUE***", "overwriteprotocol": "https", "enabledPreviewProviders": [ "OC\\Preview\\PNG", "OC\\Preview\\JPEG", "OC\\Preview\\GIF", "OC\\Preview\\HEIC", "OC\\Preview\\BMP", "OC\\Preview\\XBitmap", "OC\\Preview\\MP3", "OC\\Preview\\TXT", "OC\\Preview\\MarkDown", "OC\\Preview\\MSOffice2003", "OC\\Preview\\MSOffice2007", "OC\\Preview\\MSOfficeDoc", "OC\\Preview\\OpenDocument", "OC\\Preview\\Movie" ], "datadirectory": "***REMOVED SENSITIVE VALUE***", "dbtype": "pgsql", "version": "21.0.7.0", "overwrite.cli.url": "http:\/\/localhost", "dbname": "***REMOVED SENSITIVE VALUE***", "dbhost": "***REMOVED SENSITIVE VALUE***", "dbport": "", "dbtableprefix": "", "dbuser": "***REMOVED SENSITIVE VALUE***", "dbpassword": "***REMOVED SENSITIVE VALUE***", "installed": true, "instanceid": "***REMOVED SENSITIVE VALUE***", "mail_smtpmode": "smtp", "mail_smtpsecure": "tls", "mail_sendmailmode": "smtp", "mail_from_address": "***REMOVED SENSITIVE VALUE***", "mail_domain": "***REMOVED SENSITIVE VALUE***", "mail_smtpauthtype": "LOGIN", "mail_smtpauth": 1, "mail_smtphost": "***REMOVED SENSITIVE VALUE***", "mail_smtpport": "587", "mail_smtpname": "***REMOVED SENSITIVE VALUE***", "mail_smtppassword": "***REMOVED SENSITIVE VALUE***", "simpleSignUpLink.shown": false, "default_phone_region": "***COUNTRY***", "maintenance": false, "loglevel": 0, "memcache.distributed": "\\OC\\Memcache\\Redis", "memcache.locking": "\\OC\\Memcache\\Redis", "redis": { "host": "***REMOVED SENSITIVE VALUE***", "port": 6379 }, "theme": "" } } ```

Server configuration (decide, if you think it is helpful)

Database:

[ ] MySql version:
[ ] MariaDB version:
[x] PostgreSQL version: 10 (docker, alpine)
[ ] Oracle version:
[ ] SQLite:
[ ] Other (add name and version):

PHP version:

[ ] 7.3 or lower
[x] 7.4
[ ] 8.0

Are you using an external user-backend, if yes which one: no.

Client configuration

Device:

[x] PC
[ ] Mac
[ ] Mobile phone
[ ] Tablet

Browser:

[ ] Firefox version:
[ ] Chrome version:
[ ] Safari version:
[x] Brave version: 1.32.113 Chromium: 96.0.4664.45 (Official Build) (64-Bit)

Logs

Nextcloud log

``` [index] Error: TypeError: Return value of OCA\Polls\Db\Option::getDisplayName() must be of the type string, null returned at <> 0. /var/www/html/custom_apps/polls/lib/Db/Option.php line 116 OCA\Polls\Db\Option->getDisplayName() 1. <> OCA\Polls\Db\Option->jsonSerialize() 2. /var/www/html/lib/public/AppFramework/Http/JSONResponse.php line 73 json_encode({option: OCA\Pol ... }}, 1) 3. /var/www/html/lib/private/AppFramework/Http/Dispatcher.php line 172 OCP\AppFramework\Http\JSONResponse->render() 4. /var/www/html/lib/private/AppFramework/App.php line 157 OC\AppFramework\Http\Dispatcher->dispatch(OCA\Polls\Controller\OptionController {}, "add") 5. /var/www/html/lib/private/Route/Router.php line 303 OC\AppFramework\App::main("OCA\\Polls\\Con ... r", "add", OC\AppFramework\ ... {}, {_route: "polls.option.add"}) 6. /var/www/html/lib/base.php line 993 OC\Route\Router->match("/apps/polls/option") 7. /var/www/html/index.php line 37 OC::handleRequest() POST /apps/polls/option from xx.xx.xx.xx by xx at 2021-12-07T15:51:10+00:00 ```

Browser console log

``` /apps/polls/option:1 Failed to load resource: the server responded with a status of 500 () polls.js?v=20b34bc4-7:2 Error adding option: ```

Other browser logs

``` Insert additional logs from your browser here ```

nextcloud / polls