Error: The model user can't be found.

When navigating to the `Users` entry generated by the strapi users and permissions plugin in the `Collection Types` menu, the following error is logged:

```
error Error: The model user can't be found.
at DatabaseManager.query (/srv/app/node_modules/strapi-database/lib/database-manager.js:79:13)
at Strapi.query (/srv/app/node_modules/strapi/lib/Strapi.js:485:20)
at Object. (/srv/app/node_modules/strapi-plugin-preview-content/services/preview.js:89:71)
at step (/srv/app/node_modules/strapi-plugin-preview-content/services/preview.js:44:23)
at Object.next (/srv/app/node_modules/strapi-plugin-preview-content/services/preview.js:25:53)
at /srv/app/node_modules/strapi-plugin-preview-content/services/preview.js:19:71
at new Promise ()
at __awaiter (/srv/app/node_modules/strapi-plugin-preview-content/services/preview.js:15:12)
at Object.isPreviewable (/srv/app/node_modules/strapi-plugin-preview-content/services/preview.js:85:16)
at Object. (/srv/app/node_modules/strapi-plugin-preview-content/controllers/preview.js:60:54)
at step (/srv/app/node_modules/strapi-plugin-preview-content/controllers/preview.js:33:23)
at Object.next (/srv/app/node_modules/strapi-plugin-preview-content/controllers/preview.js:14:53)
at /srv/app/node_modules/strapi-plugin-preview-content/controllers/preview.js:8:71
at new Promise ()
at __awaiter (/srv/app/node_modules/strapi-plugin-preview-content/controllers/preview.js:4:12)
at Object.isPreviewable (/srv/app/node_modules/strapi-plugin-preview-content/controllers/preview.js:54:16)
```

Note that it does not beak the app, it is invisible on frontend, it is just visible in server traces.

Reproduce the error by opening the Users entry under Collection Types. Start with strapi-plugin-preview-content/services/preview.js, especially isPreviewable, and follow its call from controllers/preview.js; verify the navigation no longer logs the missing-model error while the app and frontend behavior remain unchanged.

Written by the indexing model from the issue text.