better error handling

bin/lessc

@@ -69,12 +69,16 @@ fs.stat(input, function (e, stats) {
                 if (err) {
                     less.writeError(err);
                 } else {
-                    css = tree.toCSS({ compress: options.compress });
-                    if (output) {
-                        fd = fs.openSync(output, "w");
-                        fs.writeSync(fd, css, 0, "utf8");
-                    } else {
-                        sys.print(css);
+                    try {
+                        css = tree.toCSS({ compress: options.compress });
+                        if (output) {
+                            fd = fs.openSync(output, "w");
+                            fs.writeSync(fd, css, 0, "utf8");
+                        } else {
+                            sys.print(css);
+                        }
+                    } catch (e) {
+                        less.writeError(e);
                     }
                 }
             });

lib/less/index.js

@@ -39,6 +39,10 @@ var less = {
         var extract = ctx.extract;
         var error = [];
 
+        if (ctx.stack) {
+            return require('sys').puts(ctx.stack);
+        }
+
         if (typeof(extract[0]) === 'string') {
             error.push(stylize((ctx.line - 1) + ' ' + extract[0], 'grey'));
         }

lib/less/parser.js

@@ -236,6 +236,7 @@ less.Parser = function Parser(env) {
                             name: "NameError",
                             message: e.message,
                             line: line,
+                            stack: e.stack,
                             column: column,
                             extract: [
                                 lines[line - 2],