Empty error message when saving / compiling .less fron VS2012

I have been using WW for some time now, and never had any issues. Until today.

When saving a .less file in VS2012, I get a very undescriptive error message:

Less compiler error in D:\Projects\Link\Content\link-v0.1.less.  Details:

 error:

When I try to compile the same file using the commandline tools, I get a different result. The commandline itself doesn't show any error messages, but the resulting .css file contains an error:

/* System.IO.FileNotFoundException: Could not load file or assembly 'FSharp.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.
File name: 'FSharp.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'
   at Mindscape.VisualSass.V8Hosting.createRequiringHost(IFileContentResolver resolver)
   at Mindscape.VisualSass.Integration.Compilation.V8BasedCompiler.InitialiseIfRequired(ICompilerContext context)
   at Mindscape.VisualSass.Integration.Compilation.V8BasedCompiler.CompileCore(String fileContent, String sourceFilePath, String rootPath, IEnumerable`1 additionalPaths, ICompilationSettings settings, ICompilerContext context, CompilationResult result)
   at Mindscape.VisualSass.Integration.Compilation.CompilerWithMinification.Compile(String text, String sourceFilePath, String rootPath, IEnumerable`1 additionalPaths, ICompilationSettings settings, ICompilerContext context, CompilationResult result)

WRN: Assembly binding logging is turned OFF.
To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1.
Note: There is some performance penalty associated with assembly bind failure logging.
To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog].
 */

I was using the latest regular version and have installed the nightly build (20130602). This made no difference.

When I manually copy FSharp.Core from the .vsix file to the Command Line installation folder I end up with the same empty error message and no .css file.

OK, I just solved this problem. Somehow a single space got introduced to one of the .less files breaking a comment into two separate characters:

//
/ /
//

This apparently produced some weird result and an unusable error message.

The fact remains though, that the Command Line tool, which I freshly installed from the nightly build, is missing the FSharp.Core assembly.

Thanks for reporting this, Ive explicitly added in FSharp.Core to the assemblies deployed in the install folder which should cater for this. We have previously assumed that this would be available in the Reference Assemblies via a VS install or similar.

This update will be available with tonights nightly build.

Jeremy

Thanks for fixing the reference.

My main concern though, is the lack of a usefull error message. When working with multiple .less files this message is completely useless. It doesn't tell me where the error occurs so I basically need to check every file by hand.

It would be a huge time saver if the error message would contain more information.

UPDATE

I just found out that my latest error message was caused by a missspelled parameter. This seems like something that could be properly reported. Please consider improving the error feedback.