restore error handler in worker.js

plugins/node_modules/ace/lib/ace/worker/worker.js

@@ -18,6 +18,17 @@ if (!window.console) {
 window.window = window;
 window.ace = window;
 
+window.onerror = function(message, file, line, col, err) {
+    postMessage({type: "error", data: {
+        message: message,
+        data: err.data,
+        file: file,
+        line: line, 
+        col: col,
+        stack: err.stack
+    }});
+};
+
 window.initSender = function initSender() {
 
     var EventEmitter = window.require("ace/lib/event_emitter").EventEmitter;