I'm really sad this mod was never coded to support store content, because some store stuff actually is quite good. I really like Errortrap, it is so well made and super helpful, but I cannot use it because it simply refuses to play nice with store objects - i.e the canning station and the cow plant, two of my faves. It's a shame, but c'est la vie, one cannot have it all.

I'm afraid you are quite in the minority there. Many of us use most or all of the premium store content and ErrorTrap together with no issues and have done so for years. Periodically the mod will produce a dereferencing log that mentions items like this, in particular those that were released late in the store contents' development cycle (like the canning station) and yes some day the mod should and likely will be updated to account for them a little bit better. But that doesn't mean they are incompatible in any way. This became a casualty of the timing of Twallan's retirement and is on our current developer's radar to address, but it was never a high priority since (or so he and the rest of us thought) nothing was really broken here.

May I ask what exactly is happening on your end?

It can't be updated for later store content. Their classes don't exist in the core. But that's beside the point. There's no known conflicts with any store content.

I could make jams with the canning station, but as soon as I try to do anything with the jam once it's in a sims inventory, it spits out an error and causes the sim to totally reset.

You could upload the script logs related to that error so we can see what might be happening there.
<a href="http://nraas.wikispaces.com/How+To+Uplo ... +Upload</a>

With the canning station in particular, many of us have found that Butterbot's Canning Station Overhaul mod adds stability to the item in addition to expanding its functionality. I never got errors prior except when sims would travel with preserved food, that was always potentially a problem before although the more recently updated mods here attempt to address that as well.
http://modthesims.info/download.php?t=580462