Load a game with 4 local (offline) players on Switch. We play from cartridge on a first generation switch, docked to a TV. 

Make sure all 4 characters are high level (we are 140+)

Give each player a cake armour from the birthday event, and a sparkler, and equip them.

Enchant some of them for good measure.

Open the blacksmith or any of the shops, particularly from the P3 or P4.

The game will crash instantly 100% of the time. It will do so even within seconds of loading the game and arriving at camp.

This occurs with resolution at 720p but also at 480p.

Unequipping all cake armour and sparkler allows us to open the shops again. I think one player with cake armour is fine.

This particular crash highlights a recurrent problem of crashes on the switch, which is getting worse with time. We tried to get another event item yesterday but couldn't complete a single mission without crashes. One of our party is still wearing the armour.

We attempted creepy crypt, doing all the nooks and crannies, and desert temple doing just critical path, and they both crashed.