chore: address linter warnings

Signed-off-by: Toni Förster <toni.foerster@gmail.com>

iOS/ShareSheet.swift

@@ -4,7 +4,7 @@ import SwiftUI
 struct ShareSheet: UIViewControllerRepresentable {
     typealias Callback = (_ activityType: UIActivity.ActivityType?,
                           _ completed: Bool,
-                          _ returnedItems: [Any]?,
+                          _ returnedItems: [Any],
                           _ error: Error?) -> Void
 
     let activityItems: [Any]
@@ -19,7 +19,10 @@ struct ShareSheet: UIViewControllerRepresentable {
         )
 
         controller.excludedActivityTypes = excludedActivityTypes
-        controller.completionWithItemsHandler = callback
+
+        controller.completionWithItemsHandler = { activityType, completed, returnedItems, error in
+            callback?(activityType, completed, returnedItems ?? [], error)
+        }
 
         return controller
     }