Cast doesn't seem to work in combination with types.references

[RickLucassen]

Bug report

• I've checked documentation and searched for existing issues
• I've made sure my project is based on the latest MST version
• Fork this code sandbox or another minimal reproduction.

Sandbox link or minimal reproduction code
https://codesandbox.io/s/mobx-state-tree-todolist-forked-zcdbg

Describe the expected behavior
I have a function that accepts an instance of a model, when calling this function from within an action on that model and passing self as an argument typescript won't accept it. So using cast would make typescript happy again.

Describe the observed behavior
Using cast doesn't work when the model has a types.references present. An error is thrown: "Two different types with this name exist, but they are unrelated."