"onConflictDoUpdate" fails with error in Array.flatMap

protected async upsert(
  data: typeof this.schema.$inferInsert | typeof this.schema.$inferInsert[]
){
  return await this.repository.insert(this.schema).values(data).onConflictDoUpdate({
    target: this.schema.id,
    set: data
  });
}

 Cannot read properties of undefined (reading 'name')
    at file:///var/task/shared/modules/syncer/handlers/sync.mjs:729:921
    at Array.flatMap (<anonymous>)
    at UDe.buildUpdateSet (file:///var/task/shared/modules/syncer/handlers/sync.mjs:729:848)
    at QueryPromise.onConflictDoUpdate (file:///var/task/shared/modules/syncer/handlers/sync.mjs:723:85175)
    at $De.upsert (file:///var/task/shared/modules/syncer/handlers/sync.mjs:730:3003)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async $De.insertScan (file:///var/task/shared/modules/syncer/handlers/sync.mjs:730:6785)