I've been thinking about how poor a decision it was for Erin to take the stand, and have decided to look at one area specifically, that of the death cap mushrooms. Before she took the stand, all we essentially knew was:
Death-cap mushrooms were in the mushroom paste
Erin had almost certainly foraged for mushrooms at some point
Defense wise, they had successfully managed to get an expert to say that it's very hard for a novice to identify mushroom types. The prosecution hadn't done a great job of proving that she had knowingly got them, or whether she even knew much about them. Some imprecise mobile tower pings, and random websites didn't make for much of a convincing argument. There was considerable doubt about whether she added them knowingly.
After being on trial, Erin has essentially given us a lot of extra information including:
Erin was quite an experienced forager
She regularly tested her foraged mushrooms
She had looked into the dangers of death-cap mushrooms
She placed them in a Tupperware box with other non-foraged mushrooms
She created a mushroom duxelle that she felt was bland after taste testing it
She added mushrooms from the Tupperware box but had forgotten they had foraged mushrooms in
After rinsing them, she chopped them and pushed them in the duxelle
It was only many days later that she suspected she might have put foraged mushrooms in
Now, if you're a juror you have to account for a much larger number of facts. Firstly, despite being an experienced forager who knew about DP, she wasn't concerned about these ones that she had picked. Also, she didn't taste these or use them at a different time. After creating the duxelle, she mustn't have retasted it to any great amount. The chopped mushrooms from the Tupperware box, didn't turn up in the examined leftovers for some reason. She must have had a poor memory to not consider afterwards that she had put foraged mushrooms in the box and subsequently the meal.
This is just one strand where she has made things much worse for herself by taking the stand. Now there are all sorts of things that seem odd that the jury have to account for when considering reasonable doubt. There are plenty of others where she has made things worse IMO: the reason for the meal invitation, why she didn't get sick/how sick she was, the lying about her illnesses etc