Replace "return {}" statement in plugins with explicit registerPlugin() function (more logical)

lib/less/environment/abstract-plugin-loader.js

@@ -12,7 +12,7 @@ function error(msg, type) {
         }
     );
 }
-AbstractPluginLoader.prototype.evalPlugin = function(contents, context, pluginOptions, fileInfo) {
+AbstractPluginLoader.prototype.evalPlugin = function(contents, context, imports, pluginOptions, fileInfo) {
 
     var loader,
         registry,
@@ -54,8 +54,11 @@ AbstractPluginLoader.prototype.evalPlugin = function(contents, context, pluginOp
     registry = functionRegistry.create();
 
     try {
-        loader = new Function("module", "require", "functions", "tree", "less", "fileInfo", contents);
-        pluginObj = loader(localModule, this.require, registry, this.less.tree, this.less, fileInfo);
+        var registerPlugin = function(obj) {
+            pluginObj = obj;
+        };
+        loader = new Function("module", "require", "registerPlugin", "functions", "tree", "less", "fileInfo", contents);
+        loader(localModule, this.require, registerPlugin, registry, this.less.tree, this.less, fileInfo);
 
         if (!pluginObj) {
             pluginObj = localModule.exports;
@@ -78,15 +81,8 @@ AbstractPluginLoader.prototype.evalPlugin = function(contents, context, pluginOp
             return new this.less.LessError({ message: "Not a valid plugin" });
         }
 
-    } catch(e) {
-        // TODO pass the error
-        console.log(e.stack);
-        return new this.less.LessError({
-            message: "Plugin evaluation error: '" + e.name + ': ' + e.message.replace(/["]/g, "'") + "'" ,
-            filename: filename,
-            line: this.line,
-            col: this.column
-        });
+    } catch (e) {
+        return new this.less.LessError(e, imports, filename);
     }
 
     return pluginObj;
@@ -102,7 +98,7 @@ AbstractPluginLoader.prototype.trySetOptions = function(plugin, filename, name,
         try {
             plugin.setOptions(options);
         }
-        catch(e) {
+        catch (e) {
             error("Error setting options on plugin " + name + '\n' + e.message);
             return null;
         }

test/browser/less/plugin/plugin.js

@@ -1,7 +1,7 @@
-return {
+registerPlugin({
     install: function(less, pluginManager, functions) {
         functions.add('func', function() {
             return less.Anonymous(location.href);
         });
     }
-}
+});

test/less/errors/plugin-1.less

@@ -0,0 +1 @@
+@plugin "plugin/plugin-error";

test/less/errors/plugin-1.txt

@@ -0,0 +1 @@
+SyntaxError: Unexpected token ) in {path}plugin/plugin-error.js

test/less/errors/plugin/plugin-error.js

@@ -0,0 +1,3 @@
+// jscs:disable
+functions.addMultiple({
+    "test-parse-error" : function() {

test/less/plugin/plugin-local.js

@@ -7,8 +7,8 @@ functions.addMultiple({
     }
 });
 
-return {
+registerPlugin({
     setOptions: function(raw) {
         // do nothing
     }
-}
+});