improve errors from imported files

lib/less/index.js

@@ -110,8 +110,7 @@ less.Parser.importer = function (file, paths, callback) {
               paths: [path.dirname(pathname)].concat(paths),
               filename: pathname
           }).parse(data, function (e, root) {
-              if (e) less.writeError(e);
-              callback(root);
+              callback(e, root);
           });
         });
     } else {

lib/less/parser.js

@@ -73,6 +73,7 @@ less.Parser = function Parser(env) {
         queue: [],                      // Files which haven't been imported yet
         files: {},                      // Holds the imported parse trees
         mime:  env && env.mime,         // MIME type of .less files
+        error: null,                    // Error in parsing/evaluating an import
         push: function (path, callback) {
             var that = this;
             this.queue.push(path);
@@ -80,11 +81,12 @@ less.Parser = function Parser(env) {
             //
             // Import a file asynchronously
             //
-            less.Parser.importer(path, this.paths, function (root) {
+            less.Parser.importer(path, this.paths, function (e, root) {
                 that.queue.splice(that.queue.indexOf(path), 1); // Remove the path from the queue
                 that.files[path] = root;                        // Store the root
 
-                callback(root);
+                if (e && !that.error) { that.error = e }
+                callback(e, root);
 
                 if (that.queue.length === 0) { finish() }       // Call `finish` if we're done importing
             }, env);
@@ -203,7 +205,7 @@ less.Parser = function Parser(env) {
 
         this.type = e.type || 'SyntaxError';
         this.message = e.message;
-        this.filename = env.filename;
+        this.filename = e.filename || env.filename;
         this.index = e.index;
         this.line = typeof(line) === 'number' ? line + 1 : null;
         this.callLine = e.call && (getLocation(e.call) + 1);
@@ -364,6 +366,9 @@ less.Parser = function Parser(env) {
                     } catch (e) {
                         throw new(LessError)(e, env);
                     }
+
+                    if (parser.imports.error) { throw parser.imports.error }
+
                     if (options.yuicompress && less.mode === 'node') {
                         return require('./cssmin').compressor.cssmin(css);
                     } else if (options.compress) {

lib/less/tree/import.js

@@ -28,10 +28,7 @@ tree.Import = function (path, imports, features) {
 
     // Only pre-compile .less files
     if (! this.css) {
-        imports.push(this.path, function (root) {
-            if (! root) {
-                throw new(Error)("Error parsing " + that.path);
-            }
+        imports.push(this.path, function (e, root) {
             that.root = root;
         });
     }