Regression in 2.1.0

[plesiecki]

Hello,

After updating to 2.1.0 I notice postcss-for fails to process this particular piece of custom css:

:root {
  @for $weight from 100 to 900 by 100 {
    --foo-$(weight): $weight;
  }
}

It fails for simpler case as well:

:root {
  @for $weight from 1 to 2 {
    --foo: $weight;
  }
}

I have postcss-for before postcss-custom-properties in my plugin list.

Stack trace

failed with "Cannot read property 'length' of undefined"
Object.split (/source/list.es6:21:30)
Object.space (/source/list.es6:68:21)
manageIterStack (.../node_modules/postcss-for/index.js:28:38)
.../node_modules/postcss-for/index.js:104:21
/source/container.es6:268:28
/source/container.es6:126:26
Rule.each (/source/container.es6:94:22)
Rule.walk (/source/container.es6:125:21)
/source/container.es6:128:32
Root.each (/source/container.es6:94:22)
Root.walk (/source/container.es6:125:21)
Root.walkAtRules (/source/container.es6:266:25)
processOriginalLoops (.../node_modules/postcss-for/index.js:101:13)
.../node_modules/postcss-for/index.js:112:9
LazyResult.run (/source/lazy-result.es6:331:20)
/source/lazy-result.es6:258:32
LazyResult.asyncTick (/source/lazy-result.es6:256:13)
/source/lazy-result.es6:270:22
LazyResult.asyncTick (/source/lazy-result.es6:256:13)
/source/lazy-result.es6:270:22
LazyResult.asyncTick (/source/lazy-result.es6:256:13)
processing.Promise.then._this2.processed (/source/lazy-result.es6:296:18)
LazyResult.async (/source/lazy-result.es6:293:27)
LazyResult.then (/source/lazy-result.es6:201:21)
_combinedTickCallback (internal/process/next_tick.js:67:7)
process._tickCallback (internal/process/next_tick.js:98:9)

[antyakushev]

@plesiecki Thank you! Please reopen if you'll still have any issues.