tunnel back to parameterised knotname crashes web export

[joningold]

the following

-> tunnel(-> knot) -> END 

=== knot
    yo.
    -> DONE 
=== tunnel (-> go )
    ->-> go

runs in inky as expected, but crashes when compiling to a playable web version with an "unknown error". Removing the

->-> (parametername)

line removes the error.