Fix race condition in MultisynqRoot session creation

[Veenoway]

Bug Fix

Problem

The setSession method in MultisynqRoot component had a race condition when called multiple times rapidly, potentially creating multiple sessions without proper cleanup.

Solution

Added error handling and session validation in setSession:

• Wrapped session creation in try/catch block
• Added check to ensure only intended session is stored in nextSessionRef
• Clean up abandoned sessions by calling leave() if another session was created in the meantime

Changes

• Added try/catch block around createMultisynqSession(args)
• Added validation check if (nextSessionRef.current === null)
• Added cleanup call newSession.leave() for abandoned sessions

Manual Testing

Verified that concurrent setSession calls don't create session leaks.

Breaking Changes

None - this is a backwards-compatible bug fix.