less 3.x throws an error if there's no return value for a node

[fpsqdb]

After upgrade to 3.0.1 from 2.7.3, less throw an error
" Cannot read property 'length' of undefined" at antd\lib\style\color\bezierEasing.less (line 1, column -1)
it works fine when I down to 2.7.3.

And this is the bezierEasing.less file:

bezierEasing.less

[matthew-dean]

Looks like the error has an error.

[seven-phases-max]

I've fixed the link in the first post. It seems they also have already fixed the issue (by adding return '' there) though it would be nice to have some feedback.

[matthew-dean]

It seems there were a few issues that this touched on.

1. not having javascriptEnabled: true and using inline JS
2. A bug introduced where the lack of a return statement from, presumably, some node or sub-node of a value property causes an error? Meaning since there wasn't a string returned, it's probably trying to get the length of that string. That one SHOULD be a pretty simple fix.

While you're reading this, do you have time to review the pile of Less bug fixes I've made recently?

[matthew-dean]

Duplicate of #3113.

[matthew-dean]

Re-opening since this is an issue in the current release, and the previous one (#3113) was thought to be related to alpha bugs.

[matthew-dean]

@seven-phases-max

I've fixed the link in the first post. It seems they also have already fixed the issue (by adding return '' there) though it would be nice to have some feedback.

Should we fix this? This seems to apply in this case to inline JS, which is deprecated.

[rjgotten]

@matthew-dean
Should we fix this?

Any custom function or visitor that manipulates the node tree into containing something that evaluates particular types of nodes to undefined can trigger this situation, I believe.

Some time ago I wrote a few custom functions that did some on the fly AST generation for some hacked together each loops that could take a ruleset as a parameter and have an @item parameter injected into it (similar to @arguments) to hold each item from the looped over list. I ran across the same issue back then due to a missed return statement on a node.

[matthew-dean]

Any custom function or visitor that manipulates the node tree into containing something that evaluates particular types of nodes to undefined can trigger this situation, I believe.

Okay, then it's worth checking out. I thought I handled null nodes, but maybe specifically it was for values of null.