Test config - panel field does not contains a valid key!

Description of the bug

When running the pipeline with the test data from the test-dataset and configuration of the test.config the following error occurs:

Container:
  quay.io/pixelgen-technologies/pixelator:0.22.1

Tip: you can replicate the issue by changing to the process work dir and entering the command `bash .command.run`
Dec-04 07:08:38.642 [Actor Thread 15] ERROR nextflow.Nextflow - Please check input samplesheet -> panel field does not contains a valid key!

Input: human-sc-immunology-spatial-proteomics
Valid options:
 -

### Command used and terminal output

```console
nextflow run 'https://github.com/nf-core/pixelator' -hub github -with-report 's3://report-test/pixelator/run-019ae82fc5697a989a9af30d3f7f8ab7/report.html' -with-timeline 's3://report-test/pixelator/run-019ae82fc5697a989a9af30d3f7f8ab7/timeline.html' -with-dag 's3://report-test/pixelator/run-019ae82fc5697a989a9af30d3f7f8ab7/dag.html' -with-trace 's3://report-test/pixelator/run-019ae82fc5697a989a9af30d3f7f8ab7/trace.tsv' -c nextflow-s3.config -c tower.config -c /vol/projects/clowm/nextflow.config -revision 1affbf6a29e608424038d17baf69cac37e2fa477 -params-file params.json

Relevant files

nextflow-debug-019ae82fc5697a989a9af30d3f7f8ab7.log

System information

Nextflow version: 25.10.0
Executor: slurm
Container engine: Docker
Version of nf-core/pixelator: 2.2.0

Start with the test-dataset and test.config, then reproduce the failure from the process work directory by running bash .command.run. Trace why the samplesheet panel value has no valid options; done means the test configuration accepts human-sc-immunology-spatial-proteomics without the reported validation error.