report better errors for uglify-js

Author: sokra

lib/optimize/UglifyJsPlugin.js

@@ -89,8 +89,18 @@ UglifyJsPlugin.prototype.apply = function(compiler) {
 						compilation.warnings.push(new Error(file + " from UglifyJs\n" + warnings.join("\n")));
 					}
 				} catch(err) {
-					err.file = file;
-					compilation.errors.push(err);
+					if(err.line) {
+						var original = sourceMap.originalPositionFor({
+							line: err.line,
+							column: err.col
+						});
+						if(original && original.source) {
+							compilation.errors.push(new Error(file + " from UglifyJs\n" + err.message + " [" + requestShortener.shorten(original.source) + ":" + original.line + "," + original.column + "]"));
+						} else {
+							compilation.errors.push(new Error(file + " from UglifyJs\n" + err.message + " [" + file + ":" + err.line + "," + err.col + "]"));
+						}
+					} else
+						compilation.errors.push(new Error(file + " from UglifyJs\n" + err.message));
 				} finally {
 					uglify.AST_Node.warn_function = oldWarnFunction;
 				}