Re-assignment of bridge interfaces should be restricted
It is possible to create an invalid config by reassigning an interface that is bridged. For example you can have LAN and WAN, and create bridge0 containing LAN and WAN, then go re-assign either WAN or LAN as bridge0, which then makes bridge0 one of the bridge member interfaces. Upon inadvertently doing this, the system froze up for me, not entirely unexpectedly. It did reboot fine after a power cycle, and if_bridge apparently ignored the request to add it to itself, as it only showed the one remaining physical interface as a member.
Need some additional input validation to prevent this type of obvious mistake, maybe just not allowing a bridge interface to be assigned to an interface which is bridged.