Better error messages

[vjpr]

npm lessc

ParseError: Unrecognised input in /xxx/app/assets/stylesheets/bootstrap/mixins.less on line 578, column 7:
577     .spanX (@index) when (@index > 0) {
578       (~".span@{index}") { .span(@index); }
579       .spanX(@index - 1);

less.rb lessc

/Users/Vaughan/.rvm/gems/ruby-2.0.0-p247/bundler/gems/less.rb-fbba0293ba88/lib/less/parser.rb:74:in `block (2 levels) in parse': Unrecognised input (Less::Error)
    from at less.Parser.parser.parse.finish (/Users/Vaughan/.rvm/gems/ruby-2.0.0-p247/bundler/gems/less.rb-fbba0293ba88/lib/less/js/lib/less/parser.js:475:21)
    from at tree.importVisitor.run (/Users/Vaughan/.rvm/gems/ruby-2.0.0-p247/bundler/gems/less.rb-fbba0293ba88/lib/less/js/lib/less/import-visitor.js:25:22)
    from at less.Parser.parser.parse (/Users/Vaughan/.rvm/gems/ruby-2.0.0-p247/bundler/gems/less.rb-fbba0293ba88/lib/less/js/lib/less/parser.js:484:22)
    from /Users/Vaughan/.rvm/gems/ruby-2.0.0-p247/bundler/gems/less.rb-fbba0293ba88/lib/less/parser.rb:64:in `block in parse'
    from /Users/Vaughan/.rvm/gems/ruby-2.0.0-p247/bundler/gems/less.rb-fbba0293ba88/lib/less/java_script/v8_context.rb:90:in `block in do_lock'
    from /Users/Vaughan/.rvm/gems/ruby-2.0.0-p247/bundler/gems/less.rb-fbba0293ba88/lib/less/java_script/v8_context.rb:88:in `call'
    from /Users/Vaughan/.rvm/gems/ruby-2.0.0-p247/bundler/gems/less.rb-fbba0293ba88/lib/less/java_script/v8_context.rb:88:in `Locker'
    from /Users/Vaughan/.rvm/gems/ruby-2.0.0-p247/bundler/gems/less.rb-fbba0293ba88/lib/less/java_script/v8_context.rb:88:in `do_lock'
    from /Users/Vaughan/.rvm/gems/ruby-2.0.0-p247/bundler/gems/less.rb-fbba0293ba88/lib/less/java_script/v8_context.rb:60:in `lock'
    from /Users/Vaughan/.rvm/gems/ruby-2.0.0-p247/bundler/gems/less.rb-fbba0293ba88/lib/less/java_script/v8_context.rb:30:in `exec'
    from /Users/Vaughan/.rvm/gems/ruby-2.0.0-p247/bundler/gems/less.rb-fbba0293ba88/lib/less/java_script.rb:26:in `exec'
    from /Users/Vaughan/.rvm/gems/ruby-2.0.0-p247/bundler/gems/less.rb-fbba0293ba88/lib/less/parser.rb:63:in `parse'
    from /Users/Vaughan/.rvm/gems/ruby-2.0.0-p247/bundler/gems/less.rb-fbba0293ba88/bin/lessc:100:in `<top (required)>'
    from /Users/Vaughan/.rvm/gems/ruby-2.0.0-p247/bin/lessc:23:in `load'
    from /Users/Vaughan/.rvm/gems/ruby-2.0.0-p247/bin/lessc:23:in `<main>'
    from /Users/Vaughan/.rvm/gems/ruby-2.0.0-p247/bin/ruby_noexec_wrapper:14:in `eval'
    from /Users/Vaughan/.rvm/gems/ruby-2.0.0-p247/bin/ruby_noexec_wrapper:14:in `<main>'

or in Rails

Unrecognized input
  (in /Users/Vaughan/dev/banky/app/assets/stylesheets/bootstrap_and_overrides.css.less)

[voidus]

I can't +1 this hard enough. Especially as ruby lessc is less permissive than npm lessc.

[cowboyd]

If anybody would like to pair up to tackle this issue, I would be happy to help.