Stopping chat after tool call causes error in next message

[AtlantisPleb]

Related to #63

Chats stop when it's pressed but if stopped in the middle of a tool call it can prevent new chats from going forward, similar to the other issue we have about chats not persisting/rehydrating tool state

The error after stop is a server error:

Error in POST function: ValidationException: A conversation must alternate between user and assistant roles. Make sure the conversation alternates between user and assistant roles and try again.

from app/api/chat/route.ts