crash in __nw_protocol_udp_finalize_output_frames_block_invoke

I have following `NWUDPSession`'s wrapper which handles my network traffic in packet tunnel provider extension:

class UDPSession: NSObject {
    private var lock = NSLock()
    private var session: NWUDPSession?

    var onDataReceived: ([Data]) -> Void = {_ in }
    
    init(withProvider provider: NEProvider?, address: String, port: String) {
        super.init()
        
        let endpoint = NWHostEndpoint(hostname: address, port: port)
        let session = provider?.createUDPSession(to: endpoint, from: nil)
        
        self.session = session
        self.setReadHandler()
    }
    
    deinit {
        cleanup()
    }
    
    func send(_ datagram: Data) -> Void {
        let currentSession = session
        currentSession?.writeDatagram(datagram) { [weak self, weak currentSession] (error) in
            if error != nil {
                self?.restartSession(currentSession)
                return
            }
        }
    }

    private func cleanup() {
        lock.lock()
        defer {
            lock.unlock()
        }

        session?.cancel()
    }

    private func setReadHandler() {
        session?.setReadHandler({ [weak self] (datagrams, error) in
            guard let data = datagrams else {
                return
            }
            self?.onDataReceived(data)

        }, maxDatagrams: 1)
    }

    private func restartSession(_ failedSession: NWUDPSession?) {
        lock.lock()
        defer {
            lock.unlock()
        }

        let currentSession = session
        guard let sessionToUpgrade = failedSession, sessionToUpgrade === currentSession else {
            return
        }

        session = NWUDPSession(upgradeFor: sessionToUpgrade)
        setReadHandler()
    }
}

Using Firebase crashlytics in my network extension I noticed the process crashes quite often. Usually the stack trace looks like this:

EXC_BAD_ACCESS KERN_PROTECTION_FAILURE 0x0000000105563f20

Crashed: com.apple.network.connections
0  libnetwork.dylib               0x1bc436b90 __nw_protocol_udp_finalize_output_frames_block_invoke + 864
1  libnetwork.dylib               0x1bc433b94 nw_protocol_udp_finalize_output_frames + 128
2  libnetwork.dylib               0x1bc4dd17c nw_flow_prepare_output_frames + 7808
3  libnetwork.dylib               0x1bc4daa98 nw_flow_service_writes + 1276
4  libnetwork.dylib               0x1bc4da11c nw_endpoint_handler_service_writes + 100
5  libnetwork.dylib               0x1bc51ceec __nw_connection_batch_block_invoke + 1248
6  libdispatch.dylib              0x1b9cbe610 _dispatch_call_block_and_release + 24
7  libdispatch.dylib              0x1b9cbf184 _dispatch_client_callout + 16
8  libdispatch.dylib              0x1b9c6d0b0 _dispatch_workloop_invoke$VARIANT$mp + 2104
9  libdispatch.dylib              0x1b9c75314 _dispatch_workloop_worker_thread + 588
10 libsystem_pthread.dylib        0x1b9d0eb88 _pthread_wqthread + 276
11 libsystem_pthread.dylib        0x1b9d11760 start_wqthread + 8

com.apple.main-thread
0  libsystem_kernel.dylib         0x1b9dc8634 mach_msg_trap + 8
1  libsystem_kernel.dylib         0x1b9dc7aa0 mach_msg + 72
2  CoreFoundation                 0x1b9f70288 __CFRunLoopServiceMachPort + 216
3  CoreFoundation                 0x1b9f6b3a8 __CFRunLoopRun + 1444
4  CoreFoundation                 0x1b9f6aadc CFRunLoopRunSpecific + 464
5  Foundation                     0x1ba2aa784 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 228
6  Foundation                     0x1ba2e4198 -[NSRunLoop(NSRunLoop) run] + 88
7  libxpc.dylib                   0x1b9bc7178 _xpc_objc_main + 304
8  libxpc.dylib                   0x1b9bc9acc xpc_main + 148
9  Foundation                     0x1ba2e62c8 +[NSXPCListener serviceListener] + 170
10 PlugInKit                      0x1c728ebb0 __PLUGINKIT_CALLING_OUT_TO_CLIENT_SUBSYSTEM_FOR_BEGINUSING__ + 31876
11 PlugInKit                      0x1c728e8bc __PLUGINKIT_CALLING_OUT_TO_CLIENT_SUBSYSTEM_FOR_BEGINUSING__ + 31120
12 PlugInKit                      0x1c728efc0 __PLUGINKIT_CALLING_OUT_TO_CLIENT_SUBSYSTEM_FOR_BEGINUSING__ + 32916
13 Foundation                     0x1ba4c1004 NSExtensionMain + 64
14 libdyld.dylib                  0x1b9df4360 start + 4

Thread
0  libsystem_kernel.dylib         0x1b9deaa7c __workq_kernreturn + 8
1  libsystem_pthread.dylib        0x1b9d0ebd4 _pthread_wqthread + 352
2  libsystem_pthread.dylib        0x1b9d11760 start_wqthread + 8

com.google.firebase.crashlytics.MachExceptionServer
0                    0x102f1f00c FIRCLSProcessRecordAllThreads + 392 (FIRCLSProcess.c:392)
1                    0x102f1f3f0 FIRCLSProcessRecordAllThreads + 423 (FIRCLSProcess.c:423)
2                    0x102f15c40 FIRCLSHandler + 34 (FIRCLSHandler.m:34)
3                    0x102f185e8 FIRCLSMachExceptionServer + 524 (FIRCLSMachException.c:524)
4  libsystem_pthread.dylib        0x1b9d0dd8c _pthread_start + 156
5  libsystem_pthread.dylib        0x1b9d1176c thread_start + 8

Thread
0  libsystem_kernel.dylib         0x1b9deaa7c __workq_kernreturn + 8
1  libsystem_pthread.dylib        0x1b9d0ebd4 _pthread_wqthread + 352
2  libsystem_pthread.dylib        0x1b9d11760 start_wqthread + 8

com.apple.NSURLConnectionLoader
0  libsystem_kernel.dylib         0x1b9dc8634 mach_msg_trap + 8
1  libsystem_kernel.dylib         0x1b9dc7aa0 mach_msg + 72
2  CoreFoundation                 0x1b9f70288 __CFRunLoopServiceMachPort + 216
3  CoreFoundation                 0x1b9f6b3a8 __CFRunLoopRun + 1444
4  CoreFoundation                 0x1b9f6aadc CFRunLoopRunSpecific + 464
5  CFNetwork                      0x1bd2344e8 (Niepełna)
6  Foundation                     0x1ba3db09c __NSThread__start__ + 848
7  libsystem_pthread.dylib        0x1b9d0dd8c _pthread_start + 156
8  libsystem_pthread.dylib        0x1b9d1176c thread_start + 8

I haven't found much on the method that crashes the extension. Could it be Firebase component's fault or is there something I could investigate further?