TypeError: Cannot read property 'isEmpty' of undefined for node.prelude.children objects

[ianvonholt]

While trying to compress a third-party library with CSSO, this error is encountered:

Compress block #1
[0.001s] init
  #trumbowyg-icons{overflow:hidden;visibility:hidden;height:0;width:0}#trumbowyg-icons svg{height:0;width:0}.trumbowyg-box *,.trumbowyg-box *::before,.trumbowyg-box *::after{-webkit-box-sizing:border-box;box-sizing:border-box}.trumbowyg-box svg{width:17px;height:100%;fill:#222}.trumbowyg-box,.trumbowyg-editor{display:block;position:relative;border:1px solid #DDD;width:100%;min-height:300px;margin:17px auto}.trumbowyg-box .trumbowyg-editor{margin:0 auto}.trumbowyg-box.trumbowyg-fullscreen{background:#FEFEFE;border:none!important}.trumbowyg-editor,.trumbowyg-textarea{position:relative;-webkit-box-sizing:border-box;box-sizing:border-box;padding:20px;min-height:300px;width:100%;border-style:none;resize:none;outline:none;overflow:auto}.trumbowyg-editor.trumbowyg-autogrow-on-enter,.trumbowyg-textarea.trumbowyg-autogrow-on-enter{-webkit-transition:height 300ms ease-out;transition:height 300ms ease-out}.trumbowyg-box-blur .trumbowyg-editor *,.trumbowyg-box-blur 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.trumbowyg-input-infos span.trumbowyg-msg-error{color:#e74c3c}.trumbowyg-modal-box label.trumbowyg-input-error input,.trumbowyg-modal-box label.trumbowyg-input-error textarea{border:1px solid #e74c3c}.trumbowyg-modal-box label.trumbowyg-input-error .trumbowyg-input-infos{margin-top:-27px}.trumbowyg-modal-box label input{position:absolute;top:0;right:0;height:27px;line-height:27px;border:1px solid #DEDEDE;background:#fff;font-size:14px;max-width:330px;width:70%;padding:0 7px;-webkit-transition:all 150ms;transition:all 150ms}.trumbowyg-modal-box label input:hover,.trumbowyg-modal-box label input:focus{outline:none;border:1px solid #95a5a6}.trumbowyg-modal-box label input:focus{background:#fbfcfc}.trumbowyg-modal-box label input[type="checkbox"]{left:5px;top:5px;right:auto}.trumbowyg-modal-box label input[type="checkbox"]+.trumbowyg-input-infos span{width:auto;padding-left:25px}.trumbowyg-modal-box .error{margin-top:25px;display:block;color:red}.trumbowyg-modal-box 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.trumbowyg-modal-button.trumbowyg-modal-submit:hover,.trumbowyg-dark .trumbowyg-modal-box .trumbowyg-modal-button.trumbowyg-modal-submit:focus{background:#25a25a}.trumbowyg-dark .trumbowyg-modal-box .trumbowyg-modal-button.trumbowyg-modal-submit:active{background:#176437}.trumbowyg-dark .trumbowyg-modal-box .trumbowyg-modal-button.trumbowyg-modal-reset{background:#333;color:#ccc}.trumbowyg-dark .trumbowyg-modal-box .trumbowyg-modal-button.trumbowyg-modal-reset:hover,.trumbowyg-dark .trumbowyg-modal-box .trumbowyg-modal-button.trumbowyg-modal-reset:focus{background:#444}.trumbowyg-dark .trumbowyg-modal-box .trumbowyg-modal-button.trumbowyg-modal-reset:active{background:#111}.trumbowyg-dark .trumbowyg-overlay{background-color:rgba(15,15,15,0.6)}

TypeError: Cannot read property 'isEmpty' of undefined
    at Object.cleanAtrule (/Users/ranku/Work/v2/ranku-manage/node_modules/csso/lib/clean/Atrule.js:60:60)
    at Object.leave (/Users/ranku/Work/v2/ranku-manage/node_modules/csso/lib/clean/index.js:16:37)
    at List.walkNode (/Users/ranku/Work/v2/ranku-manage/node_modules/css-tree/lib/walker/create.js:161:19)
    at List.each (/Users/ranku/Work/v2/ranku-manage/node_modules/css-tree/lib/utils/list.js:159:12)
    at Object.eval [as StyleSheet] (eval at createTypeIterator (/Users/ranku/Work/v2/ranku-manage/node_modules/css-tree/lib/walker/create.js:112:12), <anonymous>:5:15)
    at walkNode (/Users/ranku/Work/v2/ranku-manage/node_modules/css-tree/lib/walker/create.js:158:37)
    at walk (/Users/ranku/Work/v2/ranku-manage/node_modules/css-tree/lib/walker/create.js:214:9)
    at module.exports (/Users/ranku/Work/v2/ranku-manage/node_modules/csso/lib/clean/index.js:13:5)
    at compressChunk (/Users/ranku/Work/v2/ranku-manage/node_modules/csso/lib/compress.js:68:5)
    at compress (/Users/ranku/Work/v2/ranku-manage/node_modules/csso/lib/compress.js:153:9)

It appears that a majority of the rules in the /lib/clean directory are assuming that they are being passed a node.prelude.children object, when this is not the case.

[igoradamenko]

@lahmatiy, is it possible to merge the PR that fixes this bug?

[lahmatiy]

This PR doesn't fix all the cases. I tried to fix it, but had no enough time to finish. Will take a look next week. I'm so sorry for a very long delay with a fix. Feel free to ping me next week.

[igoradamenko]

@lahmatiy, okay, thanks. If there is an any way how I can help with this issue, feel free to point me on it.

[lahmatiy]

Fixed in 4.0.2