Fixes #3137 - Delay starting ElementCall until a sync response comes in (or a 5 second timeout)

- this will ensure that the room state is up to date before sending any call related events

ElementX/Sources/Screens/CallScreen/CallScreenViewModel.swift

@@ -31,6 +31,8 @@ class CallScreenViewModel: CallScreenViewModelType, CallScreenViewModelProtocol
         actionsSubject.eraseToAnyPublisher()
     }
     
+    private var syncUpdateCancellable: AnyCancellable?
+    
     /// Designated initialiser
     /// - Parameters:
     ///   - elementCallService: service responsible for setting up CallKit
@@ -113,7 +115,15 @@ class CallScreenViewModel: CallScreenViewModelType, CallScreenViewModelProtocol
             }
             .store(in: &cancellables)
         
-        Task {
+        // Wait for room states to be up to date before starting the call and notifying others
+        syncUpdateCancellable = clientProxy.actionsPublisher
+            .filter(\.isSyncUpdate)
+            .timeout(.seconds(5), scheduler: DispatchQueue.main)
+            .first() // Timeout will make the publisher complete, use first to handle both branches in the same place
+            .sink(receiveCompletion: { [weak self] _ in
+                Task { [weak self] in
+                    guard let self else { return }
+                    
                     let baseURL = if let elementCallBaseURLOverride {
                         elementCallBaseURLOverride
                     } else if case .success(let wellKnown) = await clientProxy.getElementWellKnown(), let wellKnownCall = wellKnown?.call {
@@ -136,8 +146,11 @@ class CallScreenViewModel: CallScreenViewModelType, CallScreenViewModelProtocol
                     
                     await elementCallService.setupCallSession(roomID: roomProxy.id, roomDisplayName: roomProxy.roomTitle)
                     
-            let _ = await roomProxy.sendCallNotificationIfNeeeded()
+                    _ = await roomProxy.sendCallNotificationIfNeeeded()
+                    
+                    syncUpdateCancellable = nil
                 }
+            }, receiveValue: { _ in })
     }
     
     override func process(viewAction: CallScreenViewAction) {

ElementX/Sources/Screens/CallScreen/View/CallScreen.swift

@@ -22,6 +22,9 @@ struct CallScreen: View {
     @ObservedObject var context: CallScreenViewModel.Context
     
     var body: some View {
+        if context.viewState.url == nil {
+            ProgressView()
+        } else {
             WebView(url: context.viewState.url, viewModelContext: context)
                 // This URL is stable, forces view reloads if this representable is ever reused for another url
                 .id(context.viewState.url)
@@ -29,6 +32,7 @@ struct CallScreen: View {
                 .presentationDragIndicator(.visible)
                 .alert(item: $context.alertInfo)
         }
+    }
 }
 
 private struct WebView: UIViewRepresentable {