Cannot read properties of undefined (reading '0')

[crapthings]

https://d2s.dschu012.dev/

i can't save after edit.

d2s.bundle.min.js:1 Uncaught (in promise) TypeError: Cannot read properties of undefined (reading '0')
    at d2s.bundle.min.js:1
    at d2s.bundle.min.js:1
    at Object.next (d2s.bundle.min.js:1)
    at d2s.bundle.min.js:1
    at new Promise (<anonymous>)
    at i (d2s.bundle.min.js:1)
    at h (d2s.bundle.min.js:1)
    at d2s.bundle.min.js:1
    at d2s.bundle.min.js:1
    at Object.next (d2s.bundle.min.js:1)

case s.Crafted:
                            for (i.WriteUInt8(void 0 !== e.rare_name_id ? e.rare_name_id : p(e.rare_name, r), 8),
                            i.WriteUInt8(void 0 !== e.rare_name_id2 ? e.rare_name_id2 : p(e.rare_name2, r), 8),
                            b = 0; b < 6; b++)
                                (u = e.magical_name_ids[b]) ? (i.WriteBit(1),
                                i.WriteUInt16(u, 11)) : i.WriteBit(0)
                        }

it looks this line failed

(u = e.magical_name_ids[b]) ? (i.WriteBit(1),