[Description]
Now check for vars/aggs in the direct arguments, and throw error if needed. Note that we allow a Var of the agg's semantic level, but not an Agg of that level. In principle such Aggs could probably be supported, but it would create an ordering dependency among the aggregates at execution time. Since the case appears neither to be required by spec nor particularly useful, we just treat it as a nested-aggregate situation.
[System Processing]
Processing will be aborted.
[Action]
To investigate the cause of the occurrence from the message, and remove cause.