Cart[70214:14267747] *** Terminating app due to uncaught exception 'RLMException', reason: 'Can only add, remove, or update subscriptions within a write subscription block.'
*** First throw call stack:
(
	0   CoreFoundation                      0x000000018040c304 __exceptionPreprocess + 172
	1   libobjc.A.dylib                     0x000000018005131c objc_exception_throw + 56
	2   Realm                               0x000000010f7bb3a4 -[RLMSyncSubscriptionSet verifyInWriteTransaction] + 72
	3   Realm                               0x000000010f7ba31c -[RLMSyncSubscriptionSet addSubscriptionWithClassName:subscriptionName:predicate:updateExisting:] + 112
	4   Realm                               0x000000010f7b8148 -[RLMSyncSubscription updateSubscriptionWithPredicate:] + 216
	5   RealmSwift                          0x000000010bf9e6fc $s10RealmSwift16SyncSubscriptionV11updateQuery6toType5whereyxm_AA0F0VySbGAHyxGcSgtSo0aB6ObjectCRbzlF + 780
...
	7   RealmSwift                          0x000000010bf9f718 $sIg_Ieg_TR + 20
	8   RealmSwift                          0x000000010bf9f770 $sIeg_IyB_TR + 24
	9   Realm                               0x000000010f7b9030 -[RLMSyncSubscriptionSet update:onComplete:] + 264
	10  RealmSwift                          0x000000010bfa1a50 $s10RealmSwift19SyncSubscriptionSetV6updateyyyyXEYaKFTY0_ + 376
...
	14  libswift_Concurrency.dylib          0x00000001ae384d0d _ZL23completeTaskWithClosurePN5swift12AsyncContextEPNS_10SwiftErrorE + 1
)

let realm = try await checkAndAddSubscription()

// Opening a realm and accessing it must be done from the same thread.
// Marking this function as `@MainActor` avoids threading-related issues.
@MainActor
func checkAndAddSubscription() async throws -> Realm {
    let realm = try await Realm(configuration: flexSyncConfig)
    let subscriptions = realm.subscriptions
    let foundSubscription = subscriptions.first(named: "user_team")
    try await subscriptions.update {
        if foundSubscription != nil {
            foundSubscription!.updateQuery(toType: Team.self, where: {
                 $0.teamName == "Developer Education"   // CRASH_HERE
            })
        } else {
            subscriptions.append(
                QuerySubscription<Team>(name: "user_team") {
                  $0.teamName == "Developer Education"
               })
        }
    }
    return realm
}