If you're powering the LEDs directly from the mains you need to use well insulated mains cable (preferably double sheathed), not just normal hook up wire.
The LEDs need to be well insulated, you need to cover each soldered connection on each leg in heat shrink, then cover both legs and the bottom 3mm of the LED in another layer of heat shink. The heat shrink mush be adhesive lined so it's not possible to slip off.
The rectifier circuit needs to be in its own plastic box and the cables going in and out need a proper strain relief.
There needs to be a fuse to prevent a fire, if a short circuit happens.
LEDs normally fail closed circuit, I don't know what the forward voltage of a failed LED is though, maybe it stays near 3.2V and it just stops working? I've no idea. All I can say is that if you de-rate the LEDs enough, then none of them should fail.