ios crash

NSDictionary *param = [arguments valueForKey:@"param"];
BOOL ret = [[BDAutoTrack sharedTrack] eventV3:event params:param];
flutter端如果传空参数，ios这里没有进行空校验，崩溃了。
[NSNull countByEnumeratingWithState:objects:count:]: unrecognized selector sent to instance 0x1dd004558

Locate the native iOS handler containing the shown NSDictionary and eventV3 call, then reproduce the crash by sending an empty param from Flutter. Trace how the empty value becomes NSNull and verify the handler no longer crashes while preserving normal event tracking; add or update a regression test if the existing test setup covers this path.

Written by the indexing model from the issue text.