Compilation error on Windows

[sanand0]

When compiling bootstrap.less on Windows using less.js-windows, I get the following error:

ERROR:
  type: Syntax
  message: 'eval' is null or not an object
  filename: D:\ext\bootstrap\less\bootstrap.less
  column: -1
  extract: ,, * Bootstrap v2.0.3

This vanishes when the following code in button.less:

.btn {

  ... // I've removed a bunch of lines here

  border-bottom-color: darken(@btnBorder, 10%);
  .border-radius(4px);
  .ie7-restore-left-whitespace(); // Give IE7 some love
  .box-shadow(~"inset 0 1px 0 rgba(255,255,255,.2), 0 1px 2px rgba(0,0,0,.05)");
}

is split into two parts:

.btn {

  ... // I've removed a bunch of lines here

  border-bottom-color: darken(@btnBorder, 10%);
  .border-radius(4px);
}

// Just breaking the previous declaration into two parts

.btn {
  .ie7-restore-left-whitespace(); // Give IE7 some love
  .box-shadow(~"inset 0 1px 0 rgba(255,255,255,.2), 0 1px 2px rgba(0,0,0,.05)");
}

Anyone knows what's causing this issue?

[mdo]

We can't offer support on the Windows build client, sorry—outside our realm. However, it seems like it's having difficulty in parsing the .box-shadow mixin's escaping. Try using this for that line instead:

@box-shadow: inset 0 1px 0 rgba(255,255,255,.2), 0 1px 2px rgba(0,0,0,.05);
.box-shadow(@shadow);

Best guess—otherwise ask on the mailing list.