Error in the BaseSkill Component?

[ShadowChemosh]

So I am adding a Racial Cust Special that acts just like a tool giving a +2 circumstance bonus to a small list of skills. So to make sure they cover the "tools" rules I copied the script from "Thieves Tools" to give myself a place to start.

Thieves Tools:
Pre-Levels/10000

doneif (field[gIsEquip].value = 0)
perform hero.childfound[skDisable].field[skToolMod].modify[+,2,"Mwk Thieves Tools"]

So it has this new "modify" function that I can't find any documentation on the wiki. But seems easy enough to understand as its giving a +2 bonus to the skToolMod field and going to have wording of "Mwk Thieves Tools". Ok seems good so far.

I put the following script on my Racial Cust Special and I get an error:
Pre-levels/10000

perform hero.childfound[skDisable].field[skToolMod].modify[+,2,"Shadow"]

And I get the following error when I add it to my character:

Attempt to use inconsistent operator for field adjustment with history tracking for field 'skToolMod'
Location: 'eval' script for Component 'BaseSkill' (Eval Script '#8') near line 5

The amount and text is added to the skill still:
Image2.png

But I need to figure out "why" or "what" is causing the BaseSkill component to toss the above error. Mathias/Aaron could you give any insights or thoughts on what is happening at line 5 that is causing the issue?

[Mathias]

This is a bug - if a field is set for "best" history tracking, which is the case for the skToolMod field, EVERY .modify[] that modifies that field must use the same modifier - +, -, * or /. The problem is that the script that says "we don't have any tools, therefore we get the -2 penalty" uses perform field[skToolMod].modify[-, 2, "No tools"].

So, because your script, at pre-levels/10000, used + on that field, the later use of - is incorrect.

The long-term solution is that the "no tools" penalty should be applied in a different way. Alternatively, we need a history tracking option other than best (personally, I think "Best" is a trap, because you can't handle things like the Fate's Favored trait, which adds a bonus to something that, for all other purposes, uses the maximum). For a short-term solution, perform hero.assign[ToolsAvail.skDisable] before Post-Attr/10000, and the fact that tools are available for this skill will mean that the penalty is not applied, so there's not a - and a + applied to the same field.

[ShadowChemosh]

Very interesting and good info. Thanks Mathias.