[FIX] web_editor: debug mode is not applied in the iframe of html field

addons/web_editor/static/src/js/backend.js

@@ -251,7 +251,7 @@ var FieldTextHtml = widget.extend({
             attr.translatable = 1;
         }
         if (session.debug) {
-            attr.debug = 1;
+            attr.debug = session.debug;
         }
 
         attr.lang = attr.enable_editor ? 'en_US' : this.session.user_context.lang;

addons/web_editor/views/iframe.xml

@@ -40,7 +40,7 @@
                 if (window.top.odoo && !window.top.odoo[callback+"_updown"]) {
                     window.top.odoo[callback+"_updown"] = function (value, fields_values) {
                         var editable = document.getElementsByClassName("o_editable")[0];
-                        if (value !== editable.innerHTML) {
+                        if (editable && value !== editable.innerHTML) {
                             editable.innerHTML = value;
                         }
                     };