If the callback throws an error and imports are syncronous, let the error fall through to the calling scope.

Author: lukeapage

lib/less/import-visitor.js

@@ -10,13 +10,19 @@
     tree.importVisitor.prototype = {
         isReplacing: true,
         run: function (root) {
-            // process the contents
-            this._visitor.visit(root);
+            var error;
+            try {
+                // process the contents
+                this._visitor.visit(root);
+            }
+            catch(e) {
+                error = e;
+            }
 
             this.isFinished = true;
 
             if (this.importCount === 0) {
-                this._finish();
+                this._finish(error);
             }
         },
         visitImport: function (importNode, visitArgs) {
@@ -43,11 +49,11 @@
                         if (e && !e.filename) { e.index = importNode.index; e.filename = importNode.currentFileInfo.filename; }
                         if (imported && !importNode.options.multiple) { importNode.skip = imported; }
 
-                        var subFinish = function() {
+                        var subFinish = function(e) {
                             importVisitor.importCount--;
 
                             if (importVisitor.importCount === 0 && importVisitor.isFinished) {
-                                importVisitor._finish();
+                                importVisitor._finish(e);
                             }
                         };
 

lib/less/parser.js

@@ -477,13 +477,8 @@ less.Parser = function Parser(env) {
             };
 
             if (env.processImports !== false) {
-                try {
-                    new tree.importVisitor(this.imports, finish)
-                        .run(root);
-                }
-                catch(e) {
-                    error = e;
-                }
+                new tree.importVisitor(this.imports, finish)
+                    .run(root);
             } else {
                 finish();
             }