[BUG]: Can't make an alias to `Reference`

[soraros]

Bug description

As title. I can't imagine the problem is exclusive to Reference.

Steps to reproduce

alias Ref = Reference           # Error. Why?
alias Ref = Reference[_]        # Works. Why? Doesn't `Reference` have 3 parameters? Maybe related to default parameter?
alias Ref = Reference[_, _]     # Works. Again, why?
alias Ref = Reference[_, _, _]  # Parser crash, hooray!

System information

Mojo 0.7.0 on Docker, Intel Mac