:onyx/max-peers is not respected

[kamituel]

If :onyx/max-peers is set for the partition table task, but :onyx/n-peers is not, the task will break with the NullPointerException that is rather hard to track since it happens within the function passed to vreset!.

The docs in the README.md should either state clearly :onyx/n-peers is a required parameter for this task, or onyx.plugin.sql/partition-table should fall back to using :onyx/max-peers if :onyx/n-peers is nil. This fix could be applied here: https://github.com/onyx-platform/onyx-sql/blob/0.13.x/src/onyx/plugin/sql.clj#L70.

E.g. this:

;; Partition up the partitions over all n-peers.
    (take-nth (:onyx/n-peers task-map)
              (drop slot-id
                    (map (fn [[l h]]
                           [l (dec (or h (inc n-max)))])
          ranges)))

Could become this:

;; Partition up the partitions over all n-peers.
    (take-nth (or (:onyx/n-peers task-map) (:onyx/max-peers task-map))
              (drop slot-id
                    (map (fn [[l h]]
                           [l (dec (or h (inc n-max)))])
          ranges)))

[lbradstreet]

Given the way it partitions the data, I think the only real fix here is to throw when onyx/n-peers is not used. Given the partitioning scheme, I think the number of peers needs to be stable.