Fix: Conditional check for null value

lib/utils/file_util.dart

@@ -51,8 +51,8 @@ Future<io.File?> getFile(
       );
       // do not cache origin file for IOS as they are immediately deleted
       // after usage
-      if (!(isOrigin && Platform.isIOS && diskFile != null)) {
-        FileLruCache.put(key, diskFile!);
+      if (!(isOrigin && Platform.isIOS) && diskFile != null) {
+        FileLruCache.put(key, diskFile);
       }
       return diskFile;
     }