Lack of "upsert"-like behaviour.

[schalkventer]

Searching the docs it seems that the only way to do upsert-like operations is directly via the utils, and not via the collection methods themselves (similar to insert and update).

This generally means the following:

• In most cases you first have to figure out whether the item exists and then call either insert or update in response.
• Then if it is an update you need to create an Object.assign(currentItem, newItem) inside the immer-like mutation (due to not being able to override root objects in immer).

This feels like something that would be a common operation, so was a bit suprised that there is no functionality to handle upserting/replacing when exists - unless there is and I missed it (which means it needs to maybe be made more clear in the docs/API).