Replaceitem - Inventory

You have to use container.X as slot for containers.

Then this is still a valid report, as inventory.X shouldn't work then.

All these slot descriptions are apparently mapping to internal slot IDs, which are not exclusive for one type, see also MC-138674.
Though I agree that it would be very helpful if the command prevented you from using a wrong slot type, however this is not what this report is about.
I think a separate report should be created for this.

I created MC-143716 for that now, please comment on it if you want to become the reporter.