has no member named 'length'

[Dowan35]

When trying to compile an esp32 wroom with arduino uno with the library AsyncTCP I have this error:

Documents\Arduino\libraries\ESPAsyncWebServer-master\src/AsyncEventSource.h:89:59: error: 'const class LinkedList<AsyncEventSourceMessage*>' has no member named 'length'
89 | size_t packetsWaiting() const { return _messageQueue.length(); }
| ^~~~~~

thanks for your help