old_contents: var path = require('path');
  var mkdirp = require('mkdirp');
  var includePathSearcher = require('include-path-searcher');
  var CachingWriter = require('broccoli-caching-writer');
  var nodeSass = require('node-sass');
  var assign = require('object-assign');
  var rsvp = require('rsvp');
  var Promise = rsvp.Promise;
  var fs = require('fs');
  var writeFile = rsvp.denodeify(fs.writeFile);
  
  module.exports = SassCompiler;
  SassCompiler.prototype = Object.create(CachingWriter.prototype);
  SassCompiler.prototype.constructor = SassCompiler;
  
  function SassCompiler (inputNodes, inputFile, outputFile, options) {
    if (!(this instanceof SassCompiler)) { return new SassCompiler(inputNodes, inputFile, outputFile, options); }
    if (!Array.isArray(inputNodes)) { throw new Error('Expected array for first argument - did you mean [tree] instead of tree?'); }
  
    CachingWriter.call(this, inputNodes, {
      annotation: options.annotation,
      cacheInclude: options.cacheInclude,
      cacheExclude: options.cacheExclude
    });
  
    this.inputFile = inputFile;
    this.outputFile = outputFile;
    options = options || {};
    this.options = {
      nodeSass: options.nodeSass
    };
  
    var sass = this.options.nodeSass || nodeSass;
  
    this.renderSass = rsvp.denodeify(sass.render);
  
    this.sassOptions = {
      importer: options.importer,
      functions: options.functions,
      indentedSyntax: options.indentedSyntax,
      omitSourceMapUrl: options.omitSourceMapUrl,
      outputStyle: options.outputStyle,
      precision: options.precision,
      sourceComments: options.sourceComments,
      sourceMap: options.sourceMap,
      sourceMapEmbed: options.sourceMapEmbed,
      sourceMapContents: options.sourceMapContents,
      sourceMapRoot: options.sourceMapRoot
    };
  }
  
  SassCompiler.prototype.build = function() {
    var destFile = path.join(this.outputPath, this.outputFile);
    var sourceMapFile = this.sassOptions.sourceMap;
  
    if (typeof sourceMapFile !== 'string') {
      sourceMapFile = destFile + '.map';
    }
  
    mkdirp.sync(path.dirname(destFile));
  
    var sassOptions = {
      file: includePathSearcher.findFileSync(this.inputFile, this.inputPaths),
      includePaths: this.inputPaths,
      outFile: destFile
    };
  
    assign(sassOptions, this.sassOptions);
  
    return this.renderSass(sassOptions).then(function(result) {
      var files = [
        writeFile(destFile, result.css)
      ];
  
      if (this.sassOptions.sourceMap && !this.sassOptions.sourceMapEmbed) {
        files.push(writeFile(sourceMapFile, result.map));
      }
  
      return Promise.all(files);
    }.bind(this));
  };
  
new_contents: var path = require('path');
  var mkdirp = require('mkdirp');
  var includePathSearcher = require('include-path-searcher');
  var CachingWriter = require('broccoli-caching-writer');
  var nodeSass = require('node-sass');
  var assign = require('object-assign');
  var rsvp = require('rsvp');
  var Promise = rsvp.Promise;
  var fs = require('fs');
  var writeFile = rsvp.denodeify(fs.writeFile);
  
  module.exports = SassCompiler;
  SassCompiler.prototype = Object.create(CachingWriter.prototype);
  SassCompiler.prototype.constructor = SassCompiler;
  
  function SassCompiler (inputNodes, inputFile, outputFile, options) {
    if (!(this instanceof SassCompiler)) { return new SassCompiler(inputNodes, inputFile, outputFile, options); }
    if (!Array.isArray(inputNodes)) { throw new Error('Expected array for first argument - did you mean [tree] instead of tree?'); }
  
    CachingWriter.call(this, inputNodes, {
      annotation: options.annotation,
      cacheInclude: options.cacheInclude,
      cacheExclude: options.cacheExclude
    });
  
    this.inputFile = inputFile;
    this.outputFile = outputFile;
    options = options || {};
    this.options = {
      nodeSass: options.nodeSass
    };
  
    var sass = this.options.nodeSass || nodeSass;
  
    this.renderSass = rsvp.denodeify(sass.render);
  
    this.sassOptions = {
      importer: options.importer,
      functions: options.functions,
      indentedSyntax: options.indentedSyntax,
      omitSourceMapUrl: options.omitSourceMapUrl,
      outputStyle: options.outputStyle,
      precision: options.precision,
      sourceComments: options.sourceComments,
      sourceMap: options.sourceMap,
      sourceMapEmbed: options.sourceMapEmbed,
      sourceMapContents: options.sourceMapContents,
      sourceMapRoot: options.sourceMapRoot
    };
  }
  
  /**
   * Mutates the error to include properties expected by Ember CLI.
   * See https://github.com/ember-cli/ember-cli/blob/master/docs/ERRORS.md#error-object
   * @param {Error} error
   */
  function rethrowBuildError(error) {
    if (typeof error === 'string') {
      throw new Error('[string exception] ' + error);
    } else {
      error.type = 'Sass Syntax Error';
      error.message = error.formatted;
      error.location = {
        line: error.line,
        column: error.column
      };
  
      throw error;
    }
  }
  
  SassCompiler.prototype.build = function() {
    var destFile = path.join(this.outputPath, this.outputFile);
    var sourceMapFile = this.sassOptions.sourceMap;
  
    if (typeof sourceMapFile !== 'string') {
      sourceMapFile = destFile + '.map';
    }
  
    mkdirp.sync(path.dirname(destFile));
  
    var sassOptions = {
      file: includePathSearcher.findFileSync(this.inputFile, this.inputPaths),
      includePaths: this.inputPaths,
      outFile: destFile
    };
  
    assign(sassOptions, this.sassOptions);
  
    return this.renderSass(sassOptions).then(function(result) {
      var files = [
        writeFile(destFile, result.css)
      ];
  
      if (this.sassOptions.sourceMap && !this.sassOptions.sourceMapEmbed) {
        files.push(writeFile(sourceMapFile, result.map));
      }
  
      return Promise.all(files);
    }.bind(this)).catch(rethrowBuildError);
  };
  
subject: fix Sass errors for better Ember CLI error messages