Startup of Backend fails when CAS is disabled

For the ARSnova Router project, I would like to disable CAS authentication since the router does not have Internet connection. (This is on purpose.)

However, the Backend fails to start when CAS is disabled in arsnova.properties. The following exception occurs:

org.springframework.beans.factory.BeanCreationException:
Error creating bean with name 'casAuthenticationFilter' defined in de.thm.arsnova.config.SecurityConfig:
Invocation of init method failed; nested exception is java.lang.IllegalArgumentException:
authenticationManager must be specified

I have disabled all but the Guest authentication:

security.guest.enabled=true
# 'false' for all others including:
security.cas.enabled=false