Error thrown when calling actor.prepareData()

[caewok]

FoundryVTT 12.331
dnd5e 4.1.2
Chrome v131.0.6778.140.
No modules.

Calling prepareData on an actor whose token is placed on the canvas throws an error. For example:

_token.actor.prepareData()
base-activity.mjs:563 Uncaught TypeError: Cannot redefine property: _inferredSource
    at Function.defineProperty (<anonymous>)
    at CheckActivity.prepareFinalData (base-activity.mjs:563:12)
    at CheckActivity.prepareFinalData (check-data.mjs:64:11)
    at ToolData.prepareFinalActivityData (activities.mjs:299:56)
    at ToolData.prepareFinalData (tool.mjs:123:10)
    at Item5e.prepareFinalAttributes (item.mjs:670:33)
    at actor.mjs:200:37
    at EmbeddedCollection.forEach (foundry-esm.js:5031:9)
    at Actor5e.prepareData (actor.mjs:200:16)
    at <anonymous>:1:14

Same for NPCs:

_token.actor.prepareData()
source-field.mjs:105 Uncaught TypeError: Cannot redefine property: source
    at Function.defineProperty (<anonymous>)
    at NPCData.shimActor (source-field.mjs:105:12)
    at NPCData.prepareBaseData (npc.mjs:324:27)
    at Actor5e.prepareData (foundry.js:10820:37)
    at Actor5e.prepareData (foundry.js:15863:11)
    at Actor5e.prepareData (flags.mjs:21:11)
    at Actor5e.prepareData (actor.mjs:199:11)
    at <anonymous>:1:14

This seems to happen when prepareFinalAttributes is called on an item with activities that were copied from an existing one (ie a cloned item).

This appears to be an error because I would expect prepareData to be idempotent and, if the data need not be prepared, it should just return. I would also expect prepareData to trigger an update if data has changed that has not yet been accounted for.

This behavior is different than what was seen in dnd5e v3. (No error was thrown in this situation.)