What does this mean: Type RangeImpl can not be used in a range unary test

I am trying to get a DMN model to execute. However, I keep getting an error message:

2022-05-26 17:49:10.351  INFO 4954 — [  restartedMain] o.s.b.a.w.s.WelcomePageHandlerMapping    : Adding welcome page: class path resource [META-INF/resources/index.html]
2022-05-26 17:49:11.438  INFO 4954 — [  restartedMain] o.s.b.d.a.OptionalLiveReloadServer       : LiveReload server is running on port 35729
2022-05-26 17:49:11.448  INFO 4954 — [  restartedMain] o.s.b.a.e.web.EndpointLinksResolver      : Exposing 2 endpoint(s) beneath base path '/actuator'
2022-05-26 17:49:11.794  INFO 4954 — [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8090 (https) with context path ''
2022-05-26 17:49:11.821  INFO 4954 — [  restartedMain] n.r.dvp.cbr.business.KogitoApplication   : Started KogitoApplication in 6.651 seconds (JVM running for 7.348)
2022-05-26 17:49:11.873  INFO 4954 — [on(1)-127.0.0.1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring DispatcherServlet 'dispatcherServlet'
2022-05-26 17:49:11.874  INFO 4954 — [on(1)-127.0.0.1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
2022-05-26 17:49:11.878  INFO 4954 — [on(1)-127.0.0.1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 3 ms
2022-05-26 17:49:39.061  INFO 4954 — [.0-8090-exec-10] o.springdoc.api.AbstractOpenApiResource  : Init duration for springdoc-openapi is: 792 ms
2022-05-26 17:50:10.379 ERROR 4954 — [0.0-8090-exec-8] o.k.d.core.ast.DMNDTExpressionEvaluator  : Type RangeImpl can not be used in a range unary test
2022-05-26 17:50:10.380  WARN 4954 — [0.0-8090-exec-8] o.k.d.core.ast.DMNDTExpressionEvaluator  : No rule matched for decision table 'valideer-mutatie-vertrek' and no default values were defined. Setting result to null.

I am clueless to what this means. I am thinking about a type error of some kind, but some additional hints in the error message would help a lot.