This pertains specifically to this code:

https://github.com/mongodb/mongo/blob/a7a795246a7ba15b36f96337c97333d1cf7f8061/src/mongo/db/query/sbe_runtime_planner.cpp#L162-L177

It is quite possible that all of the candidate plans have exited early. This could happen, for example, if the query involves a sort and all candidate plans require a blocking SORT stage. As written, the loop linked above will execute repeatedly but do nothing. Perhaps the code would be more clear if we returned early when all candidate plans have either failed or exited early?