fix: process upload only after successful remote sync (#22360)

Co-authored-by: shenlong-tanwen <139912620+shalong-tanwen@users.noreply.github.com>

mobile/lib/utils/isolate.dart

@@ -32,6 +32,7 @@ Cancelable<T?> runInIsolateGentle<T>({
   }
 
   return workerManager.executeGentle((cancelledChecker) async {
+    T? result;
     await runZonedGuarded(
       () async {
         BackgroundIsolateBinaryMessenger.ensureInitialized(token);
@@ -53,7 +54,7 @@ Cancelable<T?> runInIsolateGentle<T>({
 
         try {
           HttpSSLOptions.apply(applyNative: false);
-          return await computation(ref);
+          result = await computation(ref);
         } on CanceledError {
           log.warning("Computation cancelled ${debugLabel == null ? '' : ' for $debugLabel'}");
         } catch (error, stack) {
@@ -83,12 +84,11 @@ Cancelable<T?> runInIsolateGentle<T>({
             await Future.delayed(const Duration(seconds: 2));
           }
         }
-        return null;
       },
       (error, stack) {
         dPrint(() => "Error in isolate $debugLabel zone: $error, $stack");
       },
     );
-    return null;
+    return result;
   });
 }