BattleTech - A Time of War character sheet - Data migration script causing multiple Type Error: t is undefined

Hi all, I'm working on a data migration script for the BattleTech - A Time of War character sheet. I've finished a major update to the character skills code, but I need to migrate all the old data over to the new attribute fields. Unfortunately, when I test my migration, I keep randomly getting a Type Error: t is undefined error, and apparently it's coming from base.js:20:2689 The number of times the error occurs seems to be random, and I can't work out where it's coming from or what's causing it. I wrapped my entire migration code in a try catch, and I'm still getting the error, so I'm wondering if it's a bug in Roll20? It could also be that I'm making too many getAttrs() and setAttrs() calls; I don't know if there's some kind of limit. Here's a sample of my console output: old skill values: {"repeating_skills_-lgc1qcsdtgqqidpgr-v_skill":"art","repeating_skills_-lgc1qcsdtgqqidpgr-v_skillNotes":"Oral Traditions - not learned","repeating_skills_-lgc1qcsdtgqqidpgr-v_skillXP":"0"} sheetsandboxworker.js:917:25 old sub skill type: string sheetsandboxworker.js:922:25 skill value: art sheetsandboxworker.js:930:25 skill data: {"linkedAttributes":["dexterity_link"],"targetNumber":8,"complexity":"CB","subSkills":true,"displayName":{"art":"Art"}} sheetsandboxworker.js:951:25 skill name: art sheetsandboxworker.js:990:25 TypeError: t is undefined base.js:20:2689 migrated skill data: {"repeating_skills_-lgc1qcsdtgqqidpgr-v_skill":"art","repeating_skills_-lgc1qcsdtgqqidpgr-v_sub_skill":"Oral Traditions - not learned","repeating_skills_-lgc1qcsdtgqqidpgr-v_skill_xp":"0"} sheetsandboxworker.js:996:25 old skill values: {"repeating_skills_-lgc1uy7xmtuytewmdtn_skill":"art","repeating_skills_-lgc1uy7xmtuytewmdtn_skillNotes":"Songwriting","repeating_skills_-lgc1uy7xmtuytewmdtn_skillXP":"20"} sheetsandboxworker.js:917:25 TypeError: t is undefined base.js:20:2689 old sub skill type: string sheetsandboxworker.js:922:25 TypeError: t is undefined base.js:20:2689 skill value: art Here's my migration code: <a href="https://github.com/Skater901/roll20-character-sheets/blob/BTATOW/BattleTech-A-Time-of-War/BattleTech-A-Time-of-War.html#L1566-L1672" rel="nofollow">https://github.com/Skater901/roll20-character-sheets/blob/BTATOW/BattleTech-A-Time-of-War/BattleTech-A-Time-of-War.html#L1566-L1672</a> Thanks all.

In my experience, this is often caused by trying to migrate fields that are empty or of a different "type". &nbsp;You may want to do a typeof check and if it's empty, skip migrating it and see if that solves the problem.

That could very well explain it... I did notice it happened once when I accidentally left the XP amount blank in a skill that was being migrated. The previous skill should definitely have a skill value, and an XP value, but it may not have a Notes value. With that in mind, perhaps this is the line causing the problem? <a href="https://github.com/Skater901/roll20-character-sheets/blob/BTATOW/BattleTech-A-Time-of-War/BattleTech-A-Time-of-War.html#L1653" rel="nofollow">https://github.com/Skater901/roll20-character-sheets/blob/BTATOW/BattleTech-A-Time-of-War/BattleTech-A-Time-of-War.html#L1653</a> Everywhere else that I try to use the value of Notes I check if it's undefined first, I'm pretty sure, but here I'm not. I wouldn't think it matters if I try to put an undefined value into an object, but maybe it doesn't like that. I'll try putting a check in before assigning that value, to see if it fixes the error. Thanks for the tip. :)