Hi Phil,
We got exactly similar situation for one of the client where we wanted to allow both role addition and validity change from same request type/template.
Sharing you the analysis, hope you get some view to the issue you facing in.(for sure steps to correct each request is time taking, hence if can be handled automatically will be good).
Actually the request errors whenever a line item is found with system as entry, this is not because system shall have approver but its because the whole request goes to a stage like Role Owner. Let say a role and system is added in request, and we have stage as ROLE OWNER then role entry does find an approver but not system since the API agent ROLE owner is not relevant.
For this one, we have changed the decision table of BRF Line by Line(not sure which one you are using). In our decision table we have created a scenario, so that system entry gets routed to a path AUTO_APPROVAL (without agent, you can always add one stage as well if you want).
Feel free to let me know if you are not able to send the request entry system to another path.
Case which we handed we have added All the system(Role Connector) for routing to different paths and we have created not equal to Value of Role connector(this was able to handled system since when you add system as entry then role connector is not a value since no role-associated system)
*NOTE : You will find two entry while preparing decision table, ROLE CONNECTOR AND CONNECTOR. One means SID of role requested and other means of system.
We came to this solution since our decision table had lot of complexity, if its not clear let me know.
For your scenario, we may find a easy solution. if you need info, share decision table logic details.
Request,
Nishant