The topic pops up here and there on discourse, so people have been bitten - another one: Return type assertions with type parameters
They didn’t generate a lot of feedback – I just stumbled into them as I got the error and looked for a solution.
Don’t know what trips the compiler. Some other thread was speculating operator precedence.
Yes, maybe it has to do mostly with my coding style - parametric short-form functions with return type annotations might not be all that common 