hello,
I keep getting a error excuting null whenever I try to reload the following:

print("Initializing Thaumcraft ...");

- Wands

recipes.addShaped.mirrored(Thaumcraft:WandCasting.withTag({cap: "iron", rod: "living wood"}),
[ [Thaumcraft:WandCap, null, null],
[null, Botania:manaResource:3, null],
[null, null, Thaumcraft:WandCap]
]);

print("Finished Thaumcraft start up");

Is this an issue with my coding or a recipe that is not tweakable?

First, this repo is about ModTweaker which provides Minetweaker Support for various Craftmechanismen from Mods. Everything else is a Minetweaker issue.
Second, read https://github.com/MineTweaker/Modtweaker/wiki/Bug-Reporting-Guidelines

Sorry, the Thaumcraft wiki for mod tweaker mentioned that some recipes are not tweakable and if we had questions we should post here. Thus I have done so. I will post this over on the minetweaker issue tracker to see what they have to say.

Can you post it in the Minetweaker repo please? :)

Thanks! That fixed it. Sometimes I look at code for so long that I fail to see the obvious.

the function is recipes.addShapedMirrored not recipes.addShaped.mirrored