Fix crash in request vpn permission

This crash could occur if create intent in request vpn permission
was called while vpn permission was already approved

Fixed by returning true immediately in those cases

Author: Pururun

android/app/src/main/kotlin/net/mullvad/mullvadvpn/compose/util/RequestVpnPermission.kt

@@ -8,13 +8,21 @@ import androidx.activity.result.contract.ActivityResultContract
 
 class RequestVpnPermission : ActivityResultContract<Unit, Boolean>() {
     override fun createIntent(context: Context, input: Unit): Intent {
-        // We expect this permission to only be requested when the permission is missing, however,
-        // if it for some reason is called incorrectly we should return an empty intent so we avoid
-        // a crash.
-        return VpnService.prepare(context) ?: Intent()
+        return VpnService.prepare(context)!!
     }
 
     override fun parseResult(resultCode: Int, intent: Intent?): Boolean {
         return resultCode == Activity.RESULT_OK
     }
+
+    // We expect this permission to only be requested when the permission is missing. However,
+    // if it for some reason is called incorrectly we will skip the call to create intent
+    // to avoid crashing. The app will then proceed as the user accepted the permission.
+    override fun getSynchronousResult(context: Context, input: Unit): SynchronousResult<Boolean>? {
+        return if (VpnService.prepare(context) == null) {
+            SynchronousResult(true)
+        } else {
+            null
+        }
+    }
 }