ERROR: Undefined AST Node ASTBinaryOperator Sum (ASTNumber 1.0) (ASTNumber 1.0)

[juhp]

I am probably missing something...? On Fedora 31:

 In[1]: 1 + 1

        ┌─────────────────────────────────────────────────────────────────────────────────┐
Out[1]: │ ERROR: Undefined AST Node ASTBinaryOperator Sum (ASTNumber 1.0) (ASTNumber 1.0) │
        └─────────────────────────────────────────────────────────────────────────────────┘

I tried building both with ghc-8.6.5/cabal-install and with stack...

(BTW I got here via https://twitter.com/smdiehl/status/1217009913500786689)