fix: crash while opening terminal (#658)

Fixes #639

macos/Runner/AppDelegate.swift

@@ -6,4 +6,8 @@ class AppDelegate: FlutterAppDelegate {
   override func applicationShouldTerminateAfterLastWindowClosed(_ sender: NSApplication) -> Bool {
     return true
   }
+
+  override func applicationSupportsSecureRestorableState(_ app: NSApplication) -> Bool {
+    return true
+  }
 }