Crash if the Wi-Fi network is not connected during the start of 'spoofdpi'

### Version 1.4.0 64b5784 (homebrew) ### Country Belarus ### Operating System macOS 26.4.1 ### How are you running spoofdpi? If you run `spoofdpi` without any options, when the Wi-Fi network is not connected, it starts and crashes immediately after `udp idle timeout; value=25000ms`, at the stage of starting the server on 127.0.0.1:8080. ### Description Terminal output: ``` panic: runtime error: invalid memory address or nil pointer dereference f filter R clear ^C quit [signal SIGSEGV: segmentation violation code=0x2 addr=0x28 pc=0x1010de8a0] goroutine 1 [running]: main.runApp({0x101a2fbb8?, 0x3b442c81d70?}, {0x0, 0x0}, 0x3b442dbc030) github.com/xvzc/spoofdpi/cmd/spoofdpi/main.go:165 +0xb80 github.com/xvzc/spoofdpi/internal/config.CreateCommand.func25({0x101a2fbb8, 0x3b442c81d70}, 0x3b442ca8dc8) github.com/xvzc/spoofdpi/internal/config/cli.go:463 +0x4a0 github.com/urfave/cli/v3.(*Command).run(0x3b442ca8dc8, {0x101a2fbb8, 0x3b442c81d70}, {0x3b442bb2030, 0x1, 0x1}) github.com/urfave/cli/v3@v3.6.1/command_run.go:354 +0x1f48 github.com/urfave/cli/v3.(*Command).Run(0x101a1c4a8?, {0x101a2fb80?, 0x102095280?}, {0x3b442bb2030?, 0x7?, 0x101195aa0?}) github.com/urfave/cli/v3@v3.6.1/command_run.go:94 +0x28 main.main() github.com/xvzc/spoofdpi/cmd/spoofdpi/main.go:68 +0x70 ```