fix instance tracking

Author: afeight

Sources/CrossmintClient/SwiftUI/View+NonCustodialSigner.swift

@@ -3,23 +3,24 @@ import Logger
 import SwiftUI
 import Wallet
 
-@MainActor var instanceTrackers: [String: [InstanceTracker]] = [:]
+@MainActor var instanceTrackers: [String: Int] = [:]
 
 final class InstanceTracker: ObservableObject, Sendable {
     let instance: String
     init(name: String) {
         self.instance = name
+
         Task { @MainActor in
-            instanceTrackers[instance, default: []].append(self)
-            if instanceTrackers[instance, default: []].count > 1 {
+            instanceTrackers[instance, default: 0] += 1
+            if instanceTrackers[instance, default: 0] > 1 {
                 Logger.sdk.error("More than one instance of \(instance) created at a time. Behaviour is undefined.")
             }
         }
     }
 
     deinit {
         Task { @MainActor [instance] in
-            instanceTrackers[instance]?.popLast()
+            instanceTrackers[instance, default: 0] -= 1
         }
     }
 }