Your Question

Up until very recently I was able to change the recipes of the standard Coke Oven to give Wood Tar and Coal tar respectively, using Craft Tweaker.
Since I updated to version GTCeU 2.72 or 2.7.3 (I don't recall exactly which one), this does not work anymore.

Craft Tweaker only gives me a chat message reading:
[crafttweaker]: Error executing {[0:crafttweaker]: MyScriptFile.zs}: null, caused by java.lang.NullPointerException

Seems like it doesn't know the Coke Oven or the Wood Tar and Coal Tar anymore, as other recipe changes seem to be unaffected.
Since I haven't found any reference to any change to these in the change logs, and the fluid registry names of Wood Tar and Coal Tar seem to have stayed the same as well, I thought I'd ask you guys if you may have done any changes to how the coke ovens work, or the Craft Tweaker compatibility, or any other component that might cause this.

The reference sheet I was using is this one:
https://github.com/GregTechCEu/GregTech/wiki/CraftTweaker-for-Machines

My script looks like this:

val cokeoven as RecipeMap = <recipemap:coke_oven>;

helpers.clear(<recipemap:coke_oven>);

val charcoal = <minecraft:coal:1>;

cokeoven.recipeBuilder()
    .inputs(<ore:logWood>)
    .outputs(charcoal * 1)
    .fluidOutputs([<liquid:wood_tar> * 250])
    .duration(900)
    .buildAndRegister();

PS:
I'm using the "Ask a Question" form, instead of the "Bug Report" one, because the latter is too specific in its required form fields and wouldn't fit the content of my report very well.