Upgrading to Wallabag 2.4.3 broke the app

Hi

I upgraded my Wallabag from 2.4.2 and 2.4.3 and the app started having problems and throws these exceptions/

I host Wallabag with Apache and Mysql on Debian testing. I use the 2.4.3 version of the app on Android 18.1. This was working fine in Wallabag 2.4.2

```
Server error
wallabag.apiwrapper.exceptions.UnsuccessfulResponseException: HTTP response: 500 Internal Server Error
Stacktrace:
wallabag.apiwrapper.exceptions.UnsuccessfulResponseException: HTTP response: 500 Internal Server Error
at wallabag.apiwrapper.WallabagService.checkResponse(WallabagService.java:1525)
at wallabag.apiwrapper.WallabagService.checkResponseBody(WallabagService.java:1503)
at wallabag.apiwrapper.WallabagService.execAndCheckBody(WallabagService.java:1499)
at wallabag.apiwrapper.WallabagService.lambda$getArticles$0$WallabagService(WallabagService.java:218)
at wallabag.apiwrapper.-$$Lambda$WallabagService$PrzoUvX9wnRBX2jTxVqPJ-eD3zU.run(Unknown Source:4)
at wallabag.apiwrapper.NotFoundPolicy.call(NotFoundPolicy.java:140)
at wallabag.apiwrapper.NotFoundPolicy.call(NotFoundPolicy.java:133)
at wallabag.apiwrapper.NotFoundPolicy.call(NotFoundPolicy.java:128)
at wallabag.apiwrapper.WallabagService.getArticles(WallabagService.java:218)
at wallabag.apiwrapper.ArticlesQueryBuilder.execute(ArticlesQueryBuilder.java:282)
at wallabag.apiwrapper.ArticlesPageIterator.hasNext(ArticlesPageIterator.java:80)
at fr.gaulupeau.apps.Poche.service.workers.ArticleUpdater.performUpdate(ArticleUpdater.java:183)
at fr.gaulupeau.apps.Poche.service.workers.ArticleUpdater.update(ArticleUpdater.java:127)
at fr.gaulupeau.apps.Poche.service.workers.ArticleUpdateWorker.updateArticles(ArticleUpdateWorker.java:77)
at fr.gaulupeau.apps.Poche.service.workers.ArticleUpdateWorker.update(ArticleUpdateWorker.java:37)
at fr.gaulupeau.apps.Poche.service.tasks.UpdateArticlesTask.run(UpdateArticlesTask.java:17)
at fr.gaulupeau.apps.Poche.service.tasks.ActionRequestTask.run(ActionRequestTask.java:25)
at fr.gaulupeau.apps.Poche.service.-$$Lambda$0cveUIqKhxWljSld0gpOhfhYfj0.run(Unknown Source:2)
at fr.gaulupeau.apps.Poche.service.TaskService.run(TaskService.java:162)
at fr.gaulupeau.apps.Poche.service.TaskService.lambda$PgumDII_lptJcUDKRD70B1M_ER8(Unknown Source:0)
at fr.gaulupeau.apps.Poche.service.-$$Lambda$TaskService$PgumDII_lptJcUDKRD70B1M_ER8.run(Unknown Source:2)
at java.lang.Thread.run(Thread.java:923)

```

Start in wallabag.apiwrapper.WallabagService, especially getArticles and checkResponse, then trace the failing sync through ArticleUpdater. Reproduce an article update against Wallabag 2.4.3 with the Android app and inspect the server-side response or logs for the HTTP 500. Done means the upgrade no longer breaks article synchronization and the regression is covered by an appropriate test.

Written by the indexing model from the issue text.