Taking down a network interface causes infinite spinning loops #1028

If an existing network interface is taken down, pcap's next_packet method will indefinitely throw a generic error PcapError("The interface disappeared"), causing our associated loops to start spinning.

This issue manifests in two cases:

• the currently monitored network interface is taken down during an ongoing packet capture
• any of the system network interfaces is taken down while in the initial page of the app (this occurs after Network adapters traffic preview #1026)

Even if the interface is later brought back up, the existing capture will still return the error, and a new capture must be re-instantiated to be able to correctly read packets from the interface again.
Right now, I'm not re-instantiating the capture so this means that new packets won't be seen by Sniffnet.

Note: this is based on my observation on macOS, but behaviour could be platform-dependent.

Related issue: rust-pcap/pcap#393