Allow authors to edit broken problems in Studio.

vectordraw/public/js/vectordraw_edit.js

@@ -686,13 +686,16 @@ function VectorDrawXBlockEdit(runtime, element, init_args) {
     var fieldEditor = StudioEditableXBlockMixin(runtime, element);
 
     // Initialize WYSIWYG editor
-    var vectordraw = new VectorDraw('vectordraw', init_args.settings);
+    var vectordraw;
+    if (init_args.settings) {
+        vectordraw = new VectorDraw('vectordraw', init_args.settings);
+    }
 
     // Set up click handlers
     $('.save-button', element).on('click', function(e) {
         e.preventDefault();
         var data = {};
-        if (vectordraw.wasUsed) {
+        if (vectordraw && vectordraw.wasUsed) {
             // If author edited both initial state and result,
             // vectordraw.settings.vectors corresponds to state vectors were in
             // when author switched to result mode

vectordraw/templates/html/vectordraw_edit.html

@@ -61,6 +61,15 @@
           {% endif %}
         </li>
       {% endfor %}
+
+      {% if error %}
+
+      <div class="error-report">
+        <p>{% trans "Not displaying WYSIWYG editor: Problem contains invalid settings. Please fix them using the fields above." %}</p>
+      </div>
+
+      {% else %}
+
       <li>
         <!-- WYSIWYG editor -->
         <div class="vectordraw_block vectordraw_edit_block">
@@ -358,6 +367,9 @@
           </div>
         </div>
       </li>
+
+      {% endif %}
+
     </ul>
   </div>
 

vectordraw/vectordraw.py

@@ -446,6 +446,13 @@ class VectorDrawXBlock(StudioEditableXBlockMixin, XBlock):
             field_info = self._make_field_info(field_name, field)
             if field_info is not None:
                 context["fields"].append(field_info)
+        try:
+            settings = self.settings
+        except Exception:
+            error_type, error, tb = sys.exc_info()
+            context['error'] = error
+            context['traceback'] = traceback.format_tb(tb)
+            settings = None
         fragment.add_content(loader.render_template("templates/html/vectordraw_edit.html", context))
         # Add resources to studio_view fragment
         fragment.add_css_url(
@@ -464,7 +471,7 @@ class VectorDrawXBlock(StudioEditableXBlockMixin, XBlock):
             self.runtime.local_resource_url(self, 'public/js/vectordraw_edit.js')
         )
         fragment.initialize_js(
-            'VectorDrawXBlockEdit', {"settings": self.settings}
+            'VectorDrawXBlockEdit', {"settings": settings}
         )
         return fragment