tasks.js expects error.filename

https://github.com/Semantic-Org/Semantic-UI/blob/master/tasks/config/tasks.js#L92

This expects that the error will have a filename property. Sometimes other errors can be thrown and caught by this.

When it tries to access error.filename.match it throws.

Cannot call method ‘match’ of undefined suppressing the real error.

It should be

if(error.filename && error.filename.match(/theme.less/)) {

N.B

Because semantic doesn’t version its dependencies you can end up with gulp-autoprefixer 3.0.1 which requires node 12 and will make the semantic build process fail with:

/gulp-less/node_modules/accord/node_modules/when/lib/decorators/unhandledRejection.js:80
        throw e;
              ^
TypeError: Cannot call method 'match' of undefined

which is actually covering up the error:

[Error: no writecb in Transform class]

If you need to fix this force install gulp-autoprefixer to 2.3.1

[alxkolm]

Same problem.

Fast workaround:

rm -rf node_modules/gulp-autoprefixer
npm install gulp-autoprefixer@2.3.1

[CatalanCabbage]

Yup, I use Fomantic-UI; commented here just in case, since this bug has been carried over from Semantic to Fomantic. Anyway, to anybody with this issue, for reference: a PR has been submitted with the fix, will be released in Fomantic 2.8.x 😃