The installation-manager subsystem is currently registered when the org.jboss.prospero module is present. 

However if there is no prospero metadata present in the server installation (e.g. .installation/installer-channels.yaml) this leads to an exception being thrown when using installer commands or even when using :read-resource(recursive=true)

One way to solve this issue is to check for the required files in the server base and only register installation-manager module if those are present