Display a traceback in the GUI in case of errors

From George idea

dream/platform/__init__.py

 import json
+import traceback
 from pprint import pformat
 from flask import Flask, jsonify, redirect, url_for
 from flask import request
@@ -15,7 +16,12 @@ def front_page():
 def runSimulation():
   parameter_dict = request.json['json']
   app.logger.debug("running with:\n%s" % (pformat(parameter_dict,)))
-  return jsonify(json.loads(simulate_line_json(input_data=json.dumps(parameter_dict))))
+  try:
+    result = simulate_line_json(input_data=json.dumps(parameter_dict))
+    return jsonify(dict(success=json.loads(result)))
+  except Exception, e:
+    tb = traceback.format_exc()
+    return jsonify(dict(error=e.args[0], traceback=tb))
 
 def main(*args):
   app.run(debug=True)

dream/platform/static/src/dream_launcher.js

@@ -127,12 +127,16 @@
       function(e){
        dream_instance.runSimulation(
           function(data) {
-            $("#json_result").text(JSON.stringify(data, undefined, " "));
+            if (data['success']) {
+              $("#json_result").text(JSON.stringify(data['success'], undefined, " "));
               $.each(data.coreObject, function(idx, obj){
                  var e = $("#" + obj.id);
                  /* attach something to each corresponding core object */
                  // e.tooltip(JSON.stringify(obj['results'], undefined, " "));
               })
+            } else {
+              $("#json_result").effect('shake', 50).text(data['traceback']);
+            }
        });
        e.preventDefault();
        return false;