Internal server error when access a pad before auth

When i try to access a pad through link from a mail i get a clean white page with 'internal server error'.
After manual access the startpage and login the link works.

I think there is ah context to our settings because of no pad is anonymous accessable.

expected behavior:
Rewrite to startpage for login and then rewrite back to origin pad-URL.

used version: 2.4.1 with docker

settings:
```
CMD_DB_URL: postgres://...
CMD_SESSION_SECRET: ${SECRET}
CMD_IMAGE_UPLOAD_TYPE: filesystem
CMD_ALLOW_FREEURL: 'false'
CMD_ALLOW_ANONYMOUS: 'false'
CMD_ALLOW_ANONYMOUS_EDITS: 'false'
CMD_ALLOW_ANONYMOUS_VIEWS: 'false'
CMD_EMAIL: 'false'
CMD_LDAP_URL: ${LDAP_URL}
CMD_LDAP_BINDDN: ${LDAP_BINDDN}
CMD_LDAP_BINDCREDENTIALS: ${LDAP_BINDCREDENTIALS}
CMD_LDAP_SEARCHBASE: ${LDAP_SEARCHBASE}
CMD_LDAP_SEARCHFILTER: ${LDAP_SEARCHFILTER}
CMD_LDAP_USERIDFIELD: uid
CMD_DEFAULT_PERMISSION: limited
CMD_USECDN: 'false'
CMD_PLANTUML_SERVER: ...
```