I have it on one of my player's characters, it seems to be caused by this feat, when I remove this feat it works fine. I've troubleshot the feat and can't figure out why it's doing this:

Feat: https://www.dndbeyond.com/characters/feats/27557-blacks-song-dance

Character that breaks: https://www.dndbeyond.com/profile/Samir/characters/4427495 

Full bug report:

Error
TypeError: Cannot read property 'isPactMagicActive' of null
    at Object.se [as isLimitedUseAvailableAtScaledAmount] (https://www.dndbeyond.com/Content/1-0-428-0/React/CharacterTools/dist/characterSheet.bundle.min.js:1:209786)
    at t.value (https://www.dndbeyond.com/Content/1-0-428-0/React/CharacterTools/dist/characterSheet.bundle.min.js:51:467967)
    at f (https://www.dndbeyond.com/Content/1-0-428-0/React/CharacterTools/dist/characterSheet.bundle.min.js:25:33621)
    at beginWork (https://www.dndbeyond.com/Content/1-0-428-0/React/CharacterTools/dist/characterSheet.bundle.min.js:25:37062)
    at o (https://www.dndbeyond.com/Content/1-0-428-0/React/CharacterTools/dist/characterSheet.bundle.min.js:25:53322)
    at i (https://www.dndbeyond.com/Content/1-0-428-0/React/CharacterTools/dist/characterSheet.bundle.min.js:25:53595)
    at b (https://www.dndbeyond.com/Content/1-0-428-0/React/CharacterTools/dist/characterSheet.bundle.min.js:25:56544)
    at g (https://www.dndbeyond.com/Content/1-0-428-0/React/CharacterTools/dist/characterSheet.bundle.min.js:25:56084)
    at v (https://www.dndbeyond.com/Content/1-0-428-0/React/CharacterTools/dist/characterSheet.bundle.min.js:25:55921)
    at interactiveUpdates (https://www.dndbeyond.com/Content/1-0-428-0/React/CharacterTools/dist/characterSheet.bundle.min.js:25:59722)
Component Info

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    in Connect(t)
    in div
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    in div
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    in Connect(t)
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    in div
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Those spells in the feat, I think, should not consume spell slots, if they have a charge.

uhhh, what? I don't have the option to make that change, but also I wanted to have multiple versions where she gets 1/day cast each, and they also can add them to their spells known list. Stormknight helped me tweak some stuff, did that conflict maybe cause this issue?

If you allow me, I can try to fix it.

yes please :-)

Well, now the feat is there and the sheet does not crash.

Thanks!!