This throws the below assertion error:

    string[]@ arr;
    while (false && (@arr = cast<array<string>>(null) !is null)) {
        break;
    }

which can be avoided/fixed by adding parens around the assignment like so:

    string[]@ arr;
    while (false && ((@arr = cast<array<string>>(null)) !is null)) {
        break;
    }

originally reported on openplanet github: https://github.com/openplanet-nl/issues/issues/385