OCM. federated user gets a server crash when uploading files via tus

[ScharfViktor]

Web UI 10.3.0
Ocis: 6.5.0

Steps:
Given using server "LOCAL"
And "Alice" has generated invitation
And using server "REMOTE"
And "Brian" has accepted invitation
And using server "LOCAL"
And "Alice" shares folder f1 to "Brian"
When "Brian" tries to upload file to shared folder f1 via TUS

Actual:
server crash:

panic: runtime error: index out of range [0] with length 0
2024-10-11 09:29:30 
2024-10-11 09:29:30 goroutine 602 [running]:
2024-10-11 09:29:30 github.com/cs3org/reva/v2/pkg/rhttp/datatx/manager/tus.(*manager).Handler.func1()
2024-10-11 09:29:30     github.com/cs3org/reva/v2@v2.25.0/pkg/rhttp/datatx/manager/tus/tus.go:139 +0x31c
2024-10-11 09:29:30 created by github.com/cs3org/reva/v2/pkg/rhttp/datatx/manager/tus.(*manager).Handler in goroutine 577
2024-10-11 09:29:30     github.com/cs3org/reva/v2@v2.25.0/pkg/rhttp/datatx/manager/tus/tus.go:130 +0x354
2024-10-11 09:29:31 2024/10/11 07:29:31 INFO memory is not limited, skipping package=github.com/KimMachineGun/automemlimit/memlimit
2024-10-11 09:29:31 2024/10/11 07:29:31 Could not create config: config file already exists, use --force-overwrite to overwrite or --diff to show diff
2024-10-11 09:29:32 2024/10/11 07:29:32 INFO memory is not limited, skipping package=github.com/KimMachineGun/automemlimit/memlimit

Alice can see uploaded file. After restarting Brian instance -> file is exist
Expected: no server crash

CC @2403905

[micbar]

@2403905 Done? Please close then 😄