immerjs / immer / 37046462188

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fix: do not record a deletion when a base value is written back (#1295)

The set trap has a fast path for assigning a property its own base value
back after Immer drafted it. That path recorded the property in
`assigned_` as `false`, which patch generation reads as a deletion, so a
producer that writes a base value back and then changes anything else on
the same object emits a spurious "remove" patch. Replaying the patches
then drops a property that is still present in the produced result.

The property still holds its base value at that point, so nothing was
assigned and nothing was deleted. Remove the entry instead.

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