Crash: coercing OVal to a -> b isn't always safe; use a -> Maybe b

[julialongtin]

If you open the default object on the implicitcad website, and replace "twist(h)" with "twist(d)", the engine throws an exception

coercing OVal to a -> b isn't always safe; use a -> Maybe b (trace: -4.0 -> Execution Error:
prod takes only lists or nums )

[julialongtin]

union() {
    linear_extrude(height = 20, scale(h) = [h / 20])
    square(10);
}

returns: coercing OVal to a -> b isn't always safe; use a -> Maybe b (trace: 0.0 -> [0.0] )

[julialongtin]

linear_extrude (scale(x,y)=7) circle (10);