Bugfix: script?

修改後的結果如下：

script?: make function! [[
    {檢查是否具有有效的劇本標頭（暫時）。}
    source [file! url! binary! string!]
][
    switch type?/word source [
        file! [ source: read source ]
        url!  [ source: read source ]
        string! [ source: to-binary source]
    ]
    find-script source
]]