Issue compiling ternary ifs

[Sporarum]

On current master (a6b31a3)

interface I:
    def bar() -> DynArray[uint256, ...]: nonpayable
    def foo(xs: DynArray[uint256, ...][1]): nonpayable

@external
def f(a: address, c: bool, ys: DynArray[uint256, 5][1]):
    extcall I(a).foo([extcall I(a).bar()] if c else ys)

Fails with:

vyper.exceptions.CodegenPanic: DynArray[..., INF] don't have a size!

An xfail test is included in #5233