The bug

Frogs in boats cannot be lead out of boats using the lead as with other animals. Once in a boat, the only way to remove them is to break the boat entirely. If the player attempts to attach a lead to a single frog in a boat, the player enters the boat.

To reproduce

1. Summon a boat.
2. Summon a frog nearby, and wait for it to enter the boat.
3. Use a lead on the boat.

Observed result

You enter the boat.

Expected result

The frog would be leashed and dismounted from the boat.