Local deployment fails when benchmark parameter has no datatype

[denkv]

Description

With a parameter defined like

raki:benchmarkName a hobbit:ConfigurableParameter, hobbit:FeatureParameter;
	rdfs:label "Benchmark name"@en;
	rdfs:comment "The name of the benchmark, which is represented by an ontology and a set of positive and negative examples"@en;
	rdfs:domain hobbit:Benchmark;
	rdfs:range raki:Datasets.

parameter is sent to the GUI backend without any datatype

and that causes a NullPointerException in PlatformControllerClient.java#488.

Reproducability

Steps to reproduce the behavior:

1. Deploy the platform locally with make build start-dev-platform
2. Try to create experiment with ORCA or RAKI benchmarks
3. GUI fails to create an experiment (with an error message)

Expected behavior

The platform creates experiment normally.