Harvester leaves sim stressed

[Swanwhite]

I purchased the Stone Throw Greenhouse and have been using the gardening station and sunflowers on my home lot. I notice that if I fertilize my plants with sunshine I can harvest them multiple times a day, more times then I actually have time to.

So I decided to grab a harvester from my inventor hubbies inventory and give it a try. Well, after spinning round with the harvester a few times my sim is completely exhausted. After sucking in 5-6 plants her fun bar is completely in the red and she is too "stressed out" to do anything so I just her to a movie and she comes back all happy.

It this normal? Is it possible to have a "bad" invention like in the Sims 2? 

[Ricalynn]

This is completely normal.  Basically it means that the invention is failing.  It won't happen every time but it could happen close to.   The only harvesters that don't do this at all are the masterful ones made after completing some of the inventing skill challenges.