The <https://logstash.wikimedia.org/#/dashboard/elasticsearch/resourceloader> dashboard is filled with almost exclusively errors from MultimediaViewer about non-existent message keys being referenced.
```
MessageBlobStore::fetchMessage failed to find: 'multimediaviewer-option-header-viewer' (pt-br)
MessageBlobStore::fetchMessage failed to find: 'multimediaviewer-option-header-filepage' (pt-br)
MessageBlobStore::fetchMessage failed to find: 'multimediaviewer-option-desc-viewer' (pt-br)
MessageBlobStore::fetchMessage failed to find: 'multimediaviewer-option-desc-filepage' (pt-br)
MessageBlobStore::fetchMessage failed to find: 'multimediaviewer-license-cc-by-sa-3.0-migrated' (pt-br)
MessageBlobStore::fetchMessage failed to find: 'multimediaviewer-description-page-popup-text-local' (pt-br)
MessageBlobStore::fetchMessage failed to find: 'multimediaviewer-option-header-viewer' (zh)
MessageBlobStore::fetchMessage failed to find: 'multimediaviewer-option-header-viewer' (ja)
MessageBlobStore::fetchMessage failed to find: 'multimediaviewer-option-header-filepage' (zh)
MessageBlobStore::fetchMessage failed to find: 'multimediaviewer-option-header-filepage' (ja)
MessageBlobStore::fetchMessage failed to find: 'multimediaviewer-option-desc-viewer' (zh)
MessageBlobStore::fetchMessage failed to find: 'multimediaviewer-option-desc-viewer' (ja)
MessageBlobStore::fetchMessage failed to find: 'multimediaviewer-option-desc-filepage' (zh)
MessageBlobStore::fetchMessage failed to find: 'multimediaviewer-option-desc-filepage' (ja)
MessageBlobStore::fetchMessage failed to find: 'multimediaviewer-license-cc-by-sa-3.0-migrated' (zh)
MessageBlobStore::fetchMessage failed to find: 'multimediaviewer-license-cc-by-sa-3.0-migrated' (ja)
MessageBlobStore::fetchMessage failed to find: 'multimediaviewer-description-page-popup-text-local' (zh)
MessageBlobStore::fetchMessage failed to find: 'multimediaviewer-description-page-popup-text-local' (ja)
```
At least `multimediaviewer-option-header-viewer` doesn't seem to exist at all in i18n/en.json and was probably deleted at some point. I haven't checked the others.