In which versions of the package (and relevant enviroment tools such as Node.js) have you observed the bug?
1.7.0
What steps will reproduce the bug?
Follow README
What behavior did you expect?
No ts error
What actually happened?
Property 'addMessageListener' does not exist on type 'RPC<IframeSchema, ParentSchema>'
Workaround
No response
Proposed fix
No response
Other remarks
No response
Contribution