[Flutter] Force a username before subscribing

flutter/lib/api/api_client.dart

@@ -205,7 +205,7 @@ class APIClient {
       fn: User.fromJson,
       authToken: auth.getToken(),
       query: {
-        'confirm': ['true']
+        'confirm': ['true'],
       },
     );
   }
@@ -230,7 +230,7 @@ class APIClient {
   static Future<Client> updateClient(TokenSource auth, String clientID, {String? fcmToken, String? agentModel, String? name, String? agentVersion}) async {
     return await _request(
       name: 'updateClient',
-      method: 'PUT',
+      method: 'PATCH',
       relURL: 'users/${auth.getUserID()}/clients/$clientID',
       jsonBody: {
         if (fcmToken != null) 'fcm_token': fcmToken,
@@ -259,7 +259,7 @@ class APIClient {
       method: 'GET',
       relURL: 'users/${auth.getUserID()}/channels',
       query: {
-        'selector': [sel.apiKey]
+        'selector': [sel.apiKey],
       },
       fn: (json) => ChannelWithSubscription.fromJsonArray(json['channels'] as List<dynamic>),
       authToken: auth.getToken(),