diff --git a/js/scorm/wrapper.js b/js/scorm/wrapper.js
index 5821aff9..19bfa940 100644
--- a/js/scorm/wrapper.js
+++ b/js/scorm/wrapper.js
@@ -547,7 +547,9 @@ class ScormWrapper {
     if (!Adapt.course) return;
 
     const config = Adapt.course.get('_spoor');
-    const messages = Object.assign({}, ScormError.defaultMessages, config && config._messages);
+    const defaultMessages = ScormError.defaultMessages;
+    const configMessages = config?.['_messages'] || {};
+    const messages = Object.assign({}, defaultMessages, configMessages);
     const message = Handlebars.compile(messages[error.name])(error.data);
 
     switch (error.name) {