Public issue tracking and documentation for Foundry Virtual Tabletop - software connecting RPG gamers in a shared multiplayer environment with an intuitive interface and powerful API.
The error can be observed when toggling "Mark Defeated" in the Combat Tracker, for example:
TypeError: Failed data preparation for Combat.. Receiver must be an instance of class Combat
at Combat5e.setupTurns (foundry.js:18026:25)
at Combat5e.prepareDerivedData (foundry.js:17722:61)
at Combat5e.prepareData (foundry.js:10675:12)
at Combat5e._safePrepareData (foundry.js:10650:14)
at Combat5e._initialize (foundry.js:10481:19)
at new DataModel (foundry-esm.js:10031:12)
at new Document (foundry-esm.js:10798:3)
at new BaseCombat (foundry-esm.js:13929:7)
at new ClientDocumentMixin (foundry.js:10445:7)
at new Combat (foundry.js:17612:1)
at new Combat5e (combat.mjs:4:16)
at Combat5e.clone (foundry-esm.js:10225:14)
at Combat5e.clone (foundry-esm.js:11159:25)
at Combatant5e._preUpdateOperation (foundry.js:18590:37)
at #preUpdateDocumentArray (foundry-esm.js:56495:52)
at async ClientDatabaseBackend._updateDocuments (foundry-esm.js:56415:7)
at async Combatant5e.updateDocuments (foundry-esm.js:11278:23)
at async Combatant5e.update (foundry-esm.js:11388:23)
at async CombatTracker5e._onToggleDefeatedStatus (foundry.js:89565:5)
The error can be observed when toggling "Mark Defeated" in the Combat Tracker, for example: